GHEMI  5 TRY 


) 


THE  CHEMISTRY 

OF 

COOKING  AND  CLEANING 


A  MANUAL  FOR  HOUSEKEEPERS 


BY 


ELLEN  H.  RICHARDS 

Instructor   in   Chemistry,   Woman's  Laboratory, 
Massachusetts  Institute  of  Technology, 
Boston 


BOSTON 
ESTES   &   L AU  RI AT 

3OI   305  WASHINGTON  ST 

18S2 


Copyright  ^  1881. 
BY  ESTES  &  LAURIAT. 


PREFACE. 


JN    this  age   of   applied    science,   every  opportunity 
of    benefiting    the    household    should    be  seized 
upon. 

The  family  is  the  heart  of  the  country's  life,  and  every 
philanthropist  or  social  scientist  must  begin  at  that 
point.  Whatever,  then,  will  enlighten  the  mind,  and 
lighten  the  burden  of  care,  of  every  housekeeper  will  be 
a  boon. 

At  the  present  time,  when  the  electric  light  and 
the  gas  stove  are  familiar  topics,  there  is,  after  all,  no 
branch  of  science  which  might  be  of  more  benefit  to 
the  community,  if  it  were  properly  understood,  than 
Chemistry — the  Chemistry  of  Common  Life.  John- 
ston's excellent  book  with  that  title  deserves  a  wider 
circulation,  and  a  more  careful  study. 


viii 


PREFA  CE. 


But  there  is  a  space  yet  unoccupied  for  an  elemen- 
tary work  which  shall  give  to  non-scientific  readers 
some  practical  information  as  to  the  chemical  com- 
position of  articles  of  daily  use,  and  as  to  their  action 
in  the  various  operations  in  which  they  are  employed. 

The  public  are  the  more  ready  for  the  application 
of  this  knowledge  since  Chemistry  is  taught  in  nearly 
all  High  Schools,  and  every  child  has  a  dim  idea  of 
what  some  part  of  it  means.  To  gather  up  into  a 
definite  and  practical  form  these  indistinct  notions  is 
the  aim  of  this  little  book. 

There  is,  lingering  in  the  air,  a  great  awe  of  chem- 
istry and  chemical  terms,  an  inheritance  from  the  age 
of  alchemy.  Every  chemist  can  recall  instances  by 
the  score  in  which  manufacturers  have  asked  for 
recipes  for  making  some  substitute  for  a  well-known 
article,  and  have  expected  the  most  absurd  results  to 
follow  the  simple  mixing  of  two  substances.  Chemicals 
are  supposed  by  the  multitude  to  be  all-powerful,  and 
great  advantage  is  taken  of  this  credulity  by  unscrupulous 
manufacturers. 

The  number  of  patent  compounds  thrown  upon  the 
market  under  fanciful  and   taking  names  is  a  witness 


PREFACE. 


ix 


to  the  apathy  of  housekeepers.  It  is  time  that  they 
should  bestir  themselves  for  their  own  protection.  A 
little  knowledge  of  the  right  kind  cannot  hurt  them, 
and  it  will  surely  bring  a  large  return  in  comfort  and 
economy. 

These  mysterious  chemicals  are  not  so  many  or  so 
complicated  in  structure  but  that  a  little  patient  study 
will  enable  any  one  to  understand  the  laws  of  their 
action,  as  far  as  they  are  concerned  in  the  common 
operations  of  the  household. 

No  attempt  is  here  made  to  cover  the  whole  ground 
of  chemical  science,  but  only  to  explain  such  of  its 
principles  as  are  involved  in  the  raising  of  bread,  and 
in  a  few  other  common  processes. 


CONTENTS. 


Chap.  Page. 
I.    Introduction,    ,       ,  r 

II.    Starch,  Sugar,  and  Fat,  as  Food.      .       .  16 

III.    Nitrogenous  Food  and  t'  e  Chemistry 

of  Nutrition,  37 

PART  II. 

I.  The  Chemistry  of  Cleaning,  .  .  .  55 
II.    Chemicals  for  Household  Use,    .      .  .80 


CHAPTER  I. 


INTRODUCTION. 


E   recognize  substances,  as  we  know  people, 


by  their  characters  (properties)  and  by 
their  appearance.  Sugar  we  call  sweet ;  if  any- 
thing is  sour,  we  call  it  acid.  Sugar  and  salt 
dissolve  in  water.  Carbonic  acid  gas  will  extin- 
guish the  flame  of  a  candle.  These  are  proper- 
ties of  the  several  substances.  A  teaspoonful  of 
sugar  heated  over  a  fire  turns  black,  swells  up 
to  a  large  bulk,  emits  a  gas  which  burns  with  a 
smoky  flame,  and  finally  there  is  left  a  black, 
crumbly  mass,  which  seems  like  what  it  is,  fine 
charcoal.  There  is  nothing  which  we  consider 
sugar  left,  no  sweetness,  none  of  the  properties 
which  we  know  under  the  name  of  sugar.  There 


2 


THE  CHEMISTRY  OF 


is  a  change,  a  loss  of  identity.  This  change  is 
called  a  chemical  one. 

Add  a  solution  of  an  acid  to  a  solution  of 
an  alkali,  and  observe  that  the  acid  substance  and 
the  alkaline  substance  are  no  longer  in  existence 
as  such.  There  is,  instead,  a  neutral  saline  sub- 
stance dissolved  in  water.  The  new  substance 
has  not  the  properties  of  either  of  the  others. 
The  acid  and  the  alkali  have  both  lost  their 
identity.  A  chemical  change,  then,  involves  a  loss 
of  identity. 

"  We  must  be  very  careful  not  to  transfer  our 
ideas  of  composition,  drawn  chiefly  from  the  mix- 
tures we  use  in  common  life,  directly  to  chem- 
istry. In  these  mixtures  the  product  partakes,  to 
a  greater  or  less  degree,  of  the  character  of  its 
constituents,  which  can  be  recognized,  essentially 
unchanged,  in  the  new  material.  In  all  instances 
of  true  chemical  union  and  decomposition,  the 
qualities  of  the  substances  concerned  in  the  pro- 
cess entirely  disappear,  and  wholly  different  sub- 
stances with  new  qualities  appear  in  their  place."* 

*  "The  New  Chemistry." — Josiah  P.  Cooke.  99. 


COOKING  AND  CLEANING.  3 


All  the  substances  about  which  we  know  any- 
thing are  composed  of  a  few  elementary  bodies. 
The  grain  of  wheat,  the  flesh  of  animals,  the 
dangerous  poison,  all  are  capable  of  being  sep- 
arated into  the  simple  substances  of  which  they 
are  composed.  The  chemical  element  is  that 
substance  out  of  which  nothing  essentially  differ- 
ent *  has  ever  yet  been  obtained.  Pure  gold  is 
an  element,  a  simple  substance,  from  which  nothing 
can  be  taken  different  from  itself.  A  gold  coin 
contains  a  little  copper  or  silver,  or  both,  and  is 
not  pure  gold;  it  is  a  mixture  of  two  or  more 
elementary  substances.  The  oxygen  in  the  air  is 
an  element,  a  single  thing.  Water  is  a  compound 
of  two  elements,  oxygen  and  hydrogen,  which  are 
gases  when  they  exist  as  simple  substances. 

There  are  about  seventy  of  these  elementary 
substances  known  to  the  chemist ;  about  ten  or 
twelve  of  them  enter  into  the  compounds  which 
we  use  in  the  kitchen.  The  others  are  found  only 
in  the  chemical  laboratory  or  in  the  physician's 
medicine  case,  and  a  few  are   so  rare  as  to  be 

*  "Treatise  on  Chemistry."— Roscoe  &  Schorlemmer.  p.  51. 


4 


THE  CHEMISTRT  OF 


considered  curiosities.  Most  of  these  elements 
unite  with  each  other,  and,  in  the  compounds  thus 
formed,  other  elements  may  exchange  places  with 
those  already  there,  so  that  a  few  elementary 
bodies,  by  the  variety  of  combination,  make  up 
the  objects  of  daily  use. 

To  understand  something  of  the  nature  of  these 
chemical  substances  and  their  common  forms  is 
a  necessity  for  every  housekeeper  who  would  not 
be  cheated  of  her  money  and  her  time. 

It  is  important  for  every  one  to  remember  that 
laws  govern  all  chemical  changes ;  for  one  is  often 
asked  to  believe  that  some  chemical  sleight  of  hand 
can  make  one  pound  of  washing-soda  worth  as 
much  as  two,  and  that  some  special  preparation 
of  flour  will  give  a  third  more  bread  than  any 
other. 

As  has  been  said,  we  recognize  substances  by 
their  properties,  and  the  chemical  elements  have 
two  essential  characteristics  which  must  be  con- 
sidered at  the  outset  of  our  discussion. 

It  is  assumed  that  they  are  composed  of  homo- 
geneous particles,  the  so-called  atoms,  the  smallest 


COOKING  AND  CLEANING. 


5 


masses  of  matter  which  enter  into  chemical  com- 
bination. The  particles  have  a  definite  weight, 
constant  for  each  substance.  This  weight  is  known 
in  chemistry  as  the  atomic  weight. 

Hydrogen  being  the  lightest  substance  yet  known, 
its  atomic  weight  is  taken  as  the  unit. 

TABLE  I. 


NAME.  SYMBOL.  ATOMIC  WEIGHT. 

Hydrogen  H  i 

Sodium  (Natrium)  Na  23 

Calcium  Ca  40 

Oxygen  O  16 

Carbon  C  12 


The  atom  of  oxygen  weighs  16,  and  the  atom  of 
calcium  40  times  as  much  as  the  atom  of  hydrogen. 
The  letters  or  symbols  in  chemical  formulse  rep- 
resent this  definite  weight,  so  that  while  the  word 
oxygen  means  only  that  collection  of  properties 
to  which  we  give  the  name,  the  letter  O  in  a 
formula  indicates  also  16  times  the  weight  of  H, 
which  is  taken  as  1. 

These  symbols  give  a  definiteness  to  the  chemical 


6 


THE  CHEMISTRY  OF 


terms  which  words  merely  cannot  convey,  and 
therefore  they  are  a  great  aid  to  the  right  com- 
prehension of  the  laws  of  combination.  In  a  table 
at  the  end  of  the  book  will  be  found  the  atomic 
weight  of  all  the  elements  referred  to  in  the  text. 

The  atoms  of  each  element  have  also  their  own 
value  in  uniting  and  exchanging  places  with  the 
others. 

The  unit  of  value  is  an  arbitrary  standard.  Some- 
thing else  might  have  been  taken  than  the  unit 
chosen,  but  the  relative  value  of  all  the  elements 
as  compared  with  each  other  is  constant. 

At  the  outposts  of  the  Hudson's  Bay  Territory 
all  trade  is  on  a  system  of  barter  or  exchange,  and 
a  basis  of  value  is  necessary.  The  skin  of  a  beaver 
is  agreed  upon  as  the  unit  from  which  to  count 
all  values.  For  example  :  a  red  fox  skin  is  worth 
two  beaver  skins,  a  silver  fox  skin  is  worth 
four  beaver  skins.  All  of  the  hunter's  stock  is 
valued  in  this  way,  and  also  articles  to  be  purchased 
are  valued  by  the  same  standard,  a  knife  is  pur- 
chased for  four  beaver  skins,  a  gun  is  worth  three 
silver  fox  or  twelve  beaver  skins.     Chemists  have 


COOKING  AND  CLEANING.  7 


agreed  upon  a  unit  of  value  in  exchange,  and  the 
unit  thus  agreed  upon  is  the  atomic  weight  of 
hydrogen  above  referred  to ;  that  is,  the  smallest 
relative  weight  of  hydrogen  known  to  enter  into 
combination  with  other  elements.  It  is,  in  a  sense, 
an  arbitrary  choice,  but  having  once  accepted  it 
as  the  unit,  we  can  count  all  other  values,  in  union 
or  in  exchange,  from  its  value. 


TABLE  II. 


NAME.  SYMBOL. 

Sodium  (Natrium)  Na 
Calcium  Ca 
Oxygen  O 
Carbon  C 


NUMBER  OF  ATOMS  OF 
HYDROGEN 
WHICH  THE  ATOM  OF 
THE  SUBSTANCE  WILL  RE- 
PLACE IN  COMPOUNDS. 


For  the  convenience  of  the  reader,  this  exchange- 
able value  will  be  indicated  by  the  numbers  over 
the  letters  in  the  formulae  given  in  this  book, 
although  the  practice  is  not  universal. 

The  chemist  has  constructed  a  sign  language, 
based  upon  these  two  properties  of  the  elements, 
which    aids    the    mind    in   grasping   the   idea  of 


8 


THE  CHEMISTRY  OF 


chemical  changes.  The  symbols  are,  as  it  were, 
the  chemist's  alphabet. 

The  non-scientific  reader  is  apt  to  look  upon 
the  acquisition  of  this  sign  language  as  the 
school-boy  regards  the  study  of  Chinese  —  as  the 
work  of  a  lifetime.  While  this  view  might  not 
be  so  very  far  from  the  truth,  if  one  were  to 
attempt  to  remember  all  the  symbols  of  the  com- 
plicated compounds  which  are  possible  in  the 
union  and  interchange  of  the  seventy  or  more 
elements,  yet  the  properties  and  combinations  of 
the  dozen  of  them  which  make  up  the  common 
substances  of  daily  use  are  not  beyond  the  reach 
of  the  busy  housewife,  and  can  be  comprehended 
in  a  few  hours  of  thoughtful  reading.  "To  mas- 
ter the  symbolical  language  of  chemistry,  so  as  to 
fully  understand  what  it  expresses,  is  a  great  step 
towards  mastering  the  science."* 

Hydrogen  seems  to  be  the  connecting  link  be- 
tween the  other  elements,  which  may,  for  our 
present  purpose,  be  divided  into  two  classes,  as; 
shown  in 


*  "  The  New  Chemistry."  p.  149. 


COOKING  AND  CLEANING.  9 


TABLE  HI. 


Some  elements  which  can 

be  substituted  for 
H,  and  for  each  other  in 
chemical  compounds. 


Sodium 

Potassium 

Calcium 


EXCHANGE 
VALUE. 
I 

Na  i 


II 

Ca  2 
Hydrogen 


Some  elements  which  unite 

with  H,  and  with 
Class  I.,  as  well   as  with 
each  other. 

EXCHANGE 
VALUE. 


Chlorine 

Oxygen 

Carbon 
I 

H  ] 


I 

CI 

II 

o 

IV 

C 


I  I  II 

H    unites  with  CI,  and  forms  HC1,  or  muriatic 
I  I 
acid.    K  exchanges  places  with  H,  and  the  new 

ill  ii 
compound  is    KC1.     H2  unites  with  O,  and  forms 

1  ii  1  I 
H20,   or   water.     K2   exchanges  places   with  H2, 

I   II  IV 

and  the  new  compound   is    K20.     C  unites  with 

II  IV  II 

02  and  forms    C02,   carbon    dioxide,   or  carbonic 

IV  II  I  II 

acid   gas.     C02    unites   with  H20,  and  becomes 

I  IV  II  I 

H2C03,   or   carbonic   acid  in   solution.      Na2  ex- 
1 

changes  places  with  H2,  and   the  new  compound 


10 


THE  CHE  MIS  TR  T  OF 


I  IV  II 

is  Na2C03,  or  commercial  soda  ash,  the  compound 

with  which   the   laundress   is   familiar,   under  the 

name  of  washing  crystal. 

The   letters    mean    always    the    smallest  relative 

quantity  known   to   combine   with    anything  else, 

and  when    the    elements    combine   in   more  than 

one   proportion,   we    indicate    it    by  writing  two 

i  i 

times  or  three  times  the  units.  Thus  H2  or  2H 
means  twice  the  unit  value  of  H. 

Some  of  the  compounds  formed  by  the  union 
of  the  elements  given  in  the  Tables  are  very 
familiar  substances. 

I  ir 

H20  Water. 

1  x  2,  16    Two  parts  by  weight  of  hydrogen. 

Sixteen  parts  by  weight  of  oxygen. 
1  O  will  unite  with  2  H. 

II  II 

Ca  O  Quick-lime. 

40,  16       Forty  parts  by  weight  of  calcium. 

Sixteen  parts  by  weight  of  oxygen. 
1  Ca  will  exchange  places  with  2  H. 

IV II 

C  O2         Carbonic  acid  gas. 

12,  16  x  2  Twelve  parts  by  weight  of  carbon. 

Thirty-two  parts  by  weight  of  oxygen. 


COOKING  AND  CLEANING.  11 

The  exchanges  and  interchanges  of  the  ele- 
ments according  to  these  two  laws  of  value  and 
weight  are  chemical  reactions,  and  the  expres- 
sion of  them  is  called  a  chemical  equation.  A 
certain  modicum  of  chemical  arithmetic  is  essen- 
tial to  the  right  understanding  of  these  reactions. 

"  In  the  laboratory  we  never  mix  our  materials 
at  random,  but  always  weigh  out  the  exact  pro- 
portions .  .  .  for,  if  the  least  excess 
of  one  or  the  other  substance  over  the  propor- 
tions indicated  is  taken,  that  excess  will  be  wasted. 
It  will  not  enter  into  the  chemical  change."  * 

In  the  economy  of  nature  nothing  is  lost.  The 
wood  and  coal  burned  in  our  stoves  do  not 
vanish  into  thin  air,  without  adding  to  its  weight. 
Twelve  lbs.  of  coal  (not  counting  the  ash),  in 
burning,  take  32  lbs.  of  oxygen,  and  there  are 
formed  44  lbs.  of  carbonic  acid  gas. 

In  all  chemical  equations  there  is  just  as  much 
in  weight  represented  on  the  one  side  of  the 
sign  of  equality  (=)  as  on  the  other. 

*  "The  New  Chemistry."  /.  151. 


12 


THE  CHEMISTR  2'  OF 


For  instance,  in  the  equation 

ii        i  i  ii        ii       i  II 

HC1  +  NaHO  =  NaCl  -f  HaO 

Muriatic      Caustic         Sodium  Water. 
Acid.  Soda.         Chloride  or 

Salt. 

36.5    +    40    =    58.5    +  18 

76.5    =  76.5 

The  sum  of  the  weights  of  the  two  substances 
taken  is  equal  to  the  sum  of  the  weights  of  the 
two  new  substances  formed  as  the  result  of  the 
reaction. 

The  present  science  of  chemistry  may  be  said 
to  date  from  the  discovery  of  the  law  of  definite 
proportions,  which  gave  a  firm  basis  for  all  cal- 
culations. If  we  wish  to  obtain  44  lbs.  of  car- 
bonic acid  gas  (carbon  dioxide),  we  can  tell 
just  how  much  pure  charcoal  must  be  taken,  by 
writing  out  the  reaction  thus : 

IV        1         IV 11 

C  +  o2  =  co2 

The  atomic  weight  of  Carbon  is  12,  X  1  =  12 
The  atomic  weight  of  Oxygen  is    16,  X  2  =  32 

44 

Therefore  12  lbs.  of  charcoal  must  be  burned 
in  order  to  obtain  44  lbs.  of  carbonic  acid  gas. 


COOKING  AND  CLEANING. 


13 


This  law  of  definite  proportion  by  weight  can- 
not be  too  strongly  emphasized.  It  is  the  inva- 
riable rule  of  chemical  action,  and  it  will  be 
referred  to  again  and  again  in  discussing  the 
chemical  changes  occurring  in  cooking  and  in 
digestion. 

When  more  than  two  elements  enter  into  com- 
bination, it  is  common  for  two  or  more  to  band 
together,  and  in  this  case  the  group  has  an 
exchange  value  of  its  own,  which  is  not  the  sum 
of  the  values  of  the  separate  elements,  but  which 
is  constant,  and  dependent  upon  these  values  in 
a  way  which  it  is  not  necessary  to  explain  here. 

These  partnerships  will  be  included  in  brackets 
II          ii  i 
as    (S04)    (C03)    (N03),   not   that   these  letters 

represent  actual  compounds  existing  by  themselves, 

I  11  IV 11  11  1 
as  do  H20,  C02,  CaG2,  but  that  the  group  en- 
closed in  the  brackets  passes  from  one  compound 
into  another  as  if  it  were  only  one  element,  and 
the  numbers  over  the^  bracketed  letters  will  indi- 
cate the  exchange  value  of  the  partnership,  not 
of  the  elements  separately.  A  few  illustrations 
will  serve  to  make  this  clearer. 


14 


THE  CHEMISTRY  OF 


TABLE  IV. 

Mineral  Acids  and  Compounds : 

Till         I     II         I  II 
HC1    H(N03)    H2(S04)  H2(C03) 

Muriatic.     Nitric.        Sulphuric.  Carbonic 
I    I       I      I  II      II  II  II 

NaCl    K(N03)    Ca(S04)  Ca(C03) 

Salt.       Saltpetre.       Plaster  of  Marble. 

Paris. 

Reactions  and  Equations : 

I      II  II    II  II    II  I  II 

H,(S04)  +  Ca(CO:t)  =  Ca(S04)   -f  H2(C03) 

I     II  II  I      II  II 

H2(S04)  +  2(NaCl)    =  Na2(S04)  -f  2(HC1) 

I     II  II  I  I    II  II 

H2(S04)  +     NaCll  =NaH(,S04)+  HC1 

It  will  be  seen  that  the  groups  do  not  sep- 
arate, but  that  they  combine  with  the  single 
elements  by  the  same  law  as  that  which  governs 
the  combinations  of  the  simple  substances. 

It  is  also  to  be  observed  that  where  two  atoms 

of  hydrogen  can  be  replaced  in  a  compound,  as 
i  II 

in  112(S04),  either  one  or  both  can  be  exchanged 
for  an  atom  of  equal  replacing  value,  and  the 
two  compounds  thus  formed  will  differ  in  their 
properties.  This  will  be  shown  later  on,  in  the 
case  of  cream  of  tartar. 


OF  COOKING  AND  CLEANING. 


For  a  full  and  clear  exposition  of  the  principles 
of  the  science,  the  reader  is  referred  to  "  The 
New  Chemistry,"  by  J.  P.  Cooke. 


CHAPTER  II. 


STARCH,  SUGAR,  AND  FAT,  AS  FOOD. 

'YyHEREVER  there  is  life,  there  is  chemical 
change,  and  as  a  rule  a  certain  degree  of 
heat  is  necessary,  in  order  that  chemical  change 
may  occur.  Vegetation  does  not  begin  in  the  colder 
climates  until  the  air  becomes  warmed  by  the 
heat  of  spring.  When  the  cold  blasts  of  winter 
come  upon  the  land,  vegetation  ceases.  If  plant 
Life  is  to  be  sustained  during  a  northern  winter, 
artificial  warmth  must  be  supplied.  This  is  done 
by  keeping  up  a  furnace  or  stove  heat.  In 
chemical  terms,  carbon  from  coal,  wood,  or  gas 
is  caused  to  unite  with  the  oxygen  of  the  air  to 
form  carbonic  acid  gas,  and  by  this  union  of  two 
elements,  heat  is  produced  : 

16 


COOKING  AND  CLEANING.  17 


IV       II       IV II 

C  +  o2  =  C  o2. 
In  wood  and  gas   there   is  another  compound 
which  is  utilized : 

IV  I  II         IV II  I  II 

CH4  -f  04  ==  C02  -f  2  H20. 

These  two  chemical  reactions  express  the  changes 

which  cause  the  production  of  artificial  heat  used 

for  domestic  purposes. 

As  many  animals  live  in  temperatures  in  which 

plants  would   die,    it    is   evident   that    they  must 

have  some  source    of  heat   in   themselves.  This 

is  found  in  the  union  of  the  oxygen  of  the  air 

breathed,  with  the   carbonaceous    matter  eaten  as 

food,  and   the    formation    of    carbonic    acid  and 

IV  11  I  II 

water  (C02  and  H20),  just  as  in  the  case  of  the 

combustion  of  the  wood  in  the  grate.  Only,  in- 
stead of  this  union  taking  place  in  one  spot,  and 
so  rapidly  as  to  be  accompanied  by  light,  as  in 
the  case  of  the  grate  fire,  it  takes  place  in  each 
drop  of  the  fluid  circulating  in  the  body,  and  so 
slowly  and  continuously  as  not  to  be  noticed. 
Nevertheless  the  chemical  reaction  seems  to  be 
identical. 


18 


THE  CHE  MIS  TR  T  OF 


The  first  condition  of  animal  life  to  be  studied 
is,  then,  that  portion  of  the  food  which  supplies 
the  heat  necessary  for  the  other  chemical  changes 
to  take  place.  The  class  of  foods  which  will  be 
here  considered  as  those  for  the  production  of 
animal  heat,  includes  carbon  compounds,  chiefly 
composed  of  carbon,  hydrogen,  and  oxygen. 

These  carbonaceous  bodies  need  abundance  of 
oxygen  for  their  slow  combustion  or  oxidation, 
and  hence  the  diet  of  the  animal  must  include 
fresh  air, —  a  point  too  often  overlooked.  It  does 
not  make  a  bright  fire  to  pile  on  the  coal 
without  opening  the  draught. 

A  certain  quantity  of  heat  is  produced  by  other 
causes  than'  this  combustion  of  carbon  compounds, 
which  will  be  considered  later,  but  the  best 
authorities  seem  to  now  agree  that  the  chief  heat- 
producing  foods  used  by  the  human  race  include 
starch,  sugar,  and  fat. 

Starch  is  the  first  in  importance,  both  from  its 
wide  distribution  and  its  extensive  use.  Starch  is 
found  in  all  plants  in  greater  or  less  abundance. 
It  is  laid  up  in  large  quantities  in   the  seeds  of 


COOKING  AND  CLEANING.  19 


many  species.  Rice  is  nearly  pure  starch,  wheat 
and  the  other  cereals  contain  sixty  to  seventy 
per  cent  of  it.  Some  tubers  contain  it,  as  pota- 
toes, although  in  less  quantity,  ten  to  twenty  per 
cent.  It  is  formed  from  the  carbonic  acid  gas 
and  water  contained  in  the  air,  by  means  of  the 
living  plant-cell  and  the  sun's  rays,  and  it  is 
the  end  of  the  plant  life,  the  stored  energy  of  the 
summer,  prepared  for  the  early  life  of  the  young 
plant  another  year. 

Common  sugar,  cane-sugar,  is  found  in  fruits 
and  the  juices  of  some  plants.  It  is  directly  or 
indirectly  a  product  of  plant  life.  The  chemical 
transformations  of  starch  and  sugar  have  been 
very  carefully  and  scientifically  studied,  with  refer- 
ence to  brewing  and  wine-making. 

Several  of  the  operations  concerned  necessitate 
great  precision  in  respect  to  temperature  and 
length  of  time,  and  these  operations  bear  a  close 
analogy  to  the  process  of  bread-making  by  means 
of  yeast.  The  general  principles  on  which  the 
conversion  of  starch  into  sugar,  and  sugar  into 
alcohol,  are  conducted,  will  therefore  be  stated  as 


20 


THE  CHEMISTRY  OF 


preliminary  to  a  discussion  of  starch  and  sugar  as 
food. 

There  are  two  distinct  means  known  to  the 
chemist,  by  which  this  change  can  be  produced. 
One  is  by  the  use  of  acid  and  heat,  which 
changes  the  starch  into  sugar,  but  can  go  no 
farther.  The  other  is  by  the  use  of  a  class  of 
substances  called  ferments,  some  of  which  have 
the  power  of  changing  the  starch  into  sugar,  and 
others  of  changing  the  sugar  into  alcohol  and 
carbonic  acid  gas.  These  substances  are  in  great 
variety,  and  the  germs  of  some  of  them  are  always 
present  in  the  air. 

A  substance  is  formed  in  sprouting  grain  which 
is  called  diastase,  or  starch  converter,  which  first 
changes  the  starch  into  sugar  or  glucose,  under 
the  influence  of  warmth,  as  is  seen  in  the  pre- 
paration of  malt  for  brewing.  The  principal 
chemical .  change  is  expressed  by  the  following 
re-action : 

IV   I      II  I     II  IV    I  II 

C6  H10  Oa   -f   H2  O   +   ferment   =   C6  H12  Oe 
Starch.  Water.  Sugar  (glucose). 

The  sugar   formed   from   starch   is  one  of  the 


COOKING  AND  CLEANING.  21 


class  of  sugars   commonly  called  glucose.  These 

sugars    differ   in   some   of  their  properties  from 

ordinary  cane  sugar,  but  cane  sugar  is  easily 
changed  into  glucose  : 

IV     I      II  I    II  IV    I  II 

C,aHM0„    +   H2  O   +   ferment   —   2  C6  H12  Oe 
Cane  Sugar.  Water.  Glucose. 

So,  whether  we  start  with  starch  or  cane-sugar, 
glucose  is  produced  by  one  kind  of  fermentation, 
and  this  glucose  is  then  converted  by  yeast  into 
alcohol  and  carbonic  acid.  In  beer,  the  alcohol 
is  the  product  desired,  but  in  bread-making  the 
chief  object  of  the  fermentation  is  to  produce 
carbonic  acid  to  puff  up  the  bread,  the  alcohol 
escapes  in  the  baking. 


IV     1  11 


iv   1  11 

2  Co  HG  O 


C6     H12   Oe=   J  IVAnh°l 
Dextrose.  )     2  C  02 

^      Carbonic  Acid  Gas. 

The  alcohol,  if  burned,  would  give  carbonic 
acid  gas  and  water. 

IV    I    II  II  IV  II  I  II 

2C2H60+  12  O  =  4C02  +  6H20 

Alcohol.  Oxygen.         Carbonic  Water. 

Acid  Gas. 

It  will  be  seen  that  the  total  number  of  atoms 


22 


THE  CHEMISTRY  OF 


of  carbon  remains  constant.  There  are  six  in  the 
starch,  and  2+4=6  in  the  carbonic  acid  gas 
at  the  end,  and  but  two  atoms  of  hydrogen  have 
been  added,  while  13  atoms  of  oxygen  have  been 
required;  hence,  16  lbs.  of  starch  will  yield 
26  lbs.  of  carbonic  acid  gas  and  10.8  lbs. 
of  water,  more  than  double  the  weight  of  the 
starch.  These  products  of  decomposition  are 
given  back  to  the  air  in  the  same  form  in 
which  those  substances  existed  from  which  the 
starch  was  originally  formed. 

The  same  cycle  of  chemical  changes  goes  on 
in  the  human  body  when  starchy  substances  are 
taken  as  food.  Such  food,  moistened  and  warmed 
in  the  mouth,  becomes  mixed  with  air,  by  reason 
of  the  property  of  the  saliva  to  form  froth,  also 
it  is  impregnated  with  ptyalin,  a  substance  which 
can  change  starch  into  sugar,  as  can  the  diastase 
of  the  malt.  The  mass  then  passes  into  the  stomach, 
and  the  change  once  begun,  goes  on.  As  soon  as 
the  sugar  is  formed,  it  is  absorbed  into  the  circula- 
tory system  and  is  in  some  manner  oxidized, 
changed  into  carbonic  acid  gas  and  water. 


COOKING  AND  CLEANING.  23 


No  starch  is  used  in  the  human  system  as  such; 
it  must  undergo  this  transformation  into  sugar  be- 
fore it  can  be  absorbed.  Whatever  of  it  passes  out 
of  the  stomach  unchanged,  meets  a  very  active 
converter  in  the  pancreatic  juice.  If  grains  of 
starch  escape  these  two  agents,  they  leave  the 
system  in  the  same  form  as  that  in  which  they 
entered  it. 

The  cooking  of  pure  starch  as  rice,  farina,  etc., 
requires  little  explanation.  The  starch  grains  are 
prepared  by  the  plant  to  keep  during  a  season  of 
cold  or  drought,  and  are  very  close  and  compact; 
they  need  to  be  swollen  and  distended  by  moisture 
in  order  that  the  chemical  change  may  take  place 
readily,  as  it  is  a  law  that  the  finer  the  particles, 
the  sooner  a  given  change  takes  place.  For  in- 
stance, powdered  alum  will  dissolve  in  water  much 
sooner  than  a  crystal  of  alum,  or  marble-dust  in 
acid  sooner  than  a  piece  of  marble.  Starch  grains 
may  increase  in  bulk  twenty-five  times  in  process 
of  hydration. 

The  cooking  of  the  potato  and  other  starch- 
containing   vegetables,    is    likewise    a  mechanical 


24 


THE  CHEMISTRY  OF 


process  very  necessary  as  a  preparation  for  the 
chemical  action  of  digestion ;  for  raw  starch  has 
been  shown  to  require  a  far  longer  time  and 
more  digestive  power  than  cooked  starch.  Little 
change  can  take  place  in  the  mouth  when  the 
starch  is  not  heated  and  swollen,  and  in  case  the 
pancreatic  secretion  is  disturbed  the  starch  may 
not  become  converted  at  all. 

The  most  important  of  all  the  articles  of  diet 
which  can  be  classed  under  the  head  of  starch 
foods  is  bread.  Wheat  bread  is  not  solely  starch 
but  it  contains  a  larger  percentage  of  starch  than 
of  anything  else,  and  it  must  be  discussed  under 
this  topic. 

Bread  of  some  kind  has  been  used  by  man- 
kind from  the  first  dawn  of  civilization.  During 
the  earlier  stages  it  consisted  chiefly  of  powdered 
meal  and  water,  baked  in  the  sun,  or  on  hot 
stones.  This  kind  of  bread  had  the  same  char- 
acteristics as  the  modern  sea-biscuit,  crackers  and 
hoe-cake,  as  far  as  digestibility  was  concerned. 
It  had  great  density,  it  was  difficult  to  masticate, 
and  the   starch  in  it  presented  but  little  more 


COOKING  AND  CLEANING,  25 


surface  to  the  digestive  fluids  than  that  in  the 
hard  compact  grain,  the  seed  of  the  plant. 

Experience  must  have  taught  the  semi-civilized 
man  that  a  light  porous  loaf  was  more  digestible 
than  a  dense  one.  Probably  some  dough  was 
accidentally  left  over,  until  fermentation  had  set  in 
and  the  possibility  of  porous  bread  was  thus  sug- 
gested. 

The  ideal  loaf,  light,  spongy,  with  a  crispness 
and  sweet  pleasant  taste,  is  not  only  aesthetically, 
but  chemically,  considered  the  best  form  in  which 
starch  can  be  presented  to  the  digestive  organs. 
The  porous  condition  is  desired  in  order  that  as 
large  a  surface  as  possible  shall  be  presented  to 
the  action  of  the  chemical  converter,  the  ptyalin 
of  the  saliva.  There  is  also  a  better  aeration  in 
the  process  of  mastication. 

Very  early  in  the  history  of  the  human  race, 
leavened  bread  seems  to  have  been  used.  This 
was  made  by  allowing  flour  and  water  to  stand 
in  a  warm  place  until  decomposition  had  well  set 
in.  A  portion  of  this  dough  was  used  to  start 
fermentation   in  fresh  portions  of  flour  and  water 


26  THE  CHEMISTRY  OF 


to  be  made  into  bread.  This  kind  of  bread  had 
to  be  made  with  great  care,  lest  lactic  acid  and 
other  bodies,  unpleasant  to  the  taste,  should  be 
formed. 

Because  of  this  disagreeable  taste,  and  because 
of  the  possibility  that  the  dough  might  reach 
the  stage  of  putrid  fermentation,  chemists  and 
physicians  sought  for  some  other  means  of  ren- 
dering the  bread  light  and  porous.  The  search 
began  almost  as  soon  as  chemistry  was  worthy 
the  name  of  science,  and  one  of  the  early 
patents  bears  the  date  1837.  A  good  deal  of 
time  and  thought  has  been  devoted  to  the  per- 
fecting of  unfermented  bread ;  but  since  the 
process  of  beer  making  has  been  universally 
introduced,  yeast  has  been  readily  obtained,  and 
is  an  effectual  means  of  giving  to  the  bread  a 
pleasant  taste.  Since  the  chemistry  of  the  yeast 
fermentation  has  been  better  understood,  a  change 
of  opinion  has  come  about,  and  nearly  all  scien- 
tific and  medical  men  now  recommend  fermented 
bread. 

The  chemical  reactions  concerned  in  bread  raising 


COOKING  AND  CLEANING.  27 


are  identical  with  those  in  beer  making.  To  the 
flour  and  warmed  water  is  added  yeast,  a  sub- 
stance capable  of  causing  the  alcoholic  fermenta- 
tion. The  yeast  begins  to  act  upon  the  starch 
at  once,  especially  if  the  dough  is  of  a  semifluid 
consistency,  but  no  change  is  evident  to  the  eye 
for  some  hours,  as  the  formation  of  sugar  gives 
rise  to  no  other  products  : 


But  as  soon  as  the  sugar  is  decomposed  into 
alcohol  and  carbonic  acid  gas,  the  latter  product 
makes  itself  known  by  the  bubbles  which  appear 
and  the  consequent  swelling  of  the  whole  mass. 


It  is  the  carbonic  acid  gas  (carbon  dioxide) 
which  causes  the  sponge-like  condition  of  the  loaf 
by  reason  of  the  peculiar  tenacity  of  the  gluten, 
one  of  the  constituents  of  wheat.  It  is  a  well- 
known  fact  that  no  other  kind  of  grain  will  make 


IV  I      II  I    II        IV  I  II 


C6H10O5  +  H20  =  C6H12Os 

Starch.  Water.  Sugar. 


IV     I  II 


Carbonic  Acid  Gas. 


28 


THE  CHEMISTRY  OF 


as  light  bread  as  wheat.  It  is  the  right  propor- 
tion of  gluten  (a  nitrogenous  substance  to  be 
considered  later),  which  enables  the  light  loaf  to 
be  made  of  wheat  flour. 

The  production  of  carbonic  acid  gas  is  the  end 
of  the  chemical  process,  the  rest  is  purely  me- 
chanical. The  kneading  is  for  the  purpose  of 
rendering  the  dough  elastic  by  a  spreading  out 
and  thorough  incorporation  of  the  already  fer- 
mented mass  with  the  fresh  flour. 

Another  reason  for  kneading  is,  that  the  bubbles 
of  gas  may  be  broken  up  into  as  small  portions 
as  possible,  in  order  that  there  may  be  no  large 
holes,  but  only  very  fine  ones,  evenly  distributed 
through  the  loaf,  when  it  is  baked. 

The  temperature  at  which  the  dough  should  be 
maintained  during  the  chemical  process,  is  the 
most  important  point.  A  lesson  can  be  learned 
from  the  distillers  of  spirit.  The  best  temperature 
for  the  first  stage  of  the  alcoholic  fermentation 
is  700  to  750  F.,  the  maximum  is  820  to  900. 
Above  900,  the  production  of  acetic  acid  is  liable 
to  occur. 


COOKING  AND  CLEANING.  29 


IV  I     II  II  IV   I    II  I  II 

C2  H6  O   -f-  02   =   C2  H4  02   +   H2  O. 

Alcohol.  Acetic  Acid. 

The  more  dense  the  dough,  the  more  yeast  is 
needed.  After  the  dough  is  stiffened  by  the  fresh 
flour  and  is  nearly  ready  for  the  oven,  the  tem- 
perature may  be  raised  to  1600  or  1650  F.,  the 
temperature  of  the  beer  mash.  A  quick  change 
then  occurs  which  is  so  soon  stopped  by  the  heat 
of  the  oven,  that  no  time  is  allowed  for  souring. 

In  the  use  of  leaven,  the  lactic  fermentation 
is  liable  to  take  place,  because  sour  dough  often 
contains  a  ferment  different  from  ordinary  yeast, 
and  this  produces  a  different  set  of  reactions. 

The  temperature  should  be  carefully  regulated,  if 
light  and  sweet  bread  is  desired.  The  baking  of 
the  loaf  has  for  its  object  to  kill  the  ferment, 
to  heat  the  starch  sufficiently  to  render  it  easily 
soluble,  to  expand  the  carbonic  acid  gas  and 
drive  off  the  alcohol,  and  to  form  a  crust  which 
shall  have  a  pleasant  flavor.  The  oven  must  be 
hot  enough  to  raise  the  temperature  of  the  inside 
of  the  loaf  to  2120  F.  The  most  favorable  tem- 
perature for  baking  is  4000  to  5500  F. 


30 


THE  CHE  MIS  TR  T  OF 


The  brown  coloration  of  the  crust,  which  gives 
a  peculiar  flavor  to  the  loaf,  is  probably  caused 
by  decomposition  due  to  the  high  heat.  Some 
dextrine  may  be  formed.  One  hundred  pounds  of 
flour  are  said  to  make  from  126  to  150  pounds 
of  bread.  This  increase  of  weight  is  due  to  the 
incorporation  of  water,  very  possibly  by  a  chem- 
ical union,  as  the  water  does  not  dry  out  of  the 
loaf  as  it  does  out  of  a  sponge. 

The  bread  seems  moist  when  first  taken  from 
the  oven,  and  dry  after  standing  some  hours,  but 
the  weight  will  be  found  nearly  the  same.  It  is 
this  probable  chemical  change  which  makes  the 
difference,  to  delicate  stomachs,  between  fresh  bread 
and  stale.  A  thick  loaf  is  best  eaten  after  it  is 
twenty-four  hours  old,  although  it  is  said  to  be 
"  done,"  when  ten  hours  have  passed.  Thin  biscuits 
do  not  show  the  same  ill  effects  when  eaten  hot. 
The  bread  must  be  well  baked  in  any  case,  in  order 
that  the  process  of  fermentation  may  be  stopped. 

The  expansion  of  water  or  ice  into  1700  times 
its  volume  of  steam  is  sometimes  taken  advantage 
of  in   making   snow-bread,  water   gems,   etc.  It 


COOKING  AND  CLEANING.  31 


plays  a  part  in  the  lightening  of  pastry  and  of 
crackers. 

Air,  at  700,  expands  to  about  three  times  its 
volume  at  the  temperature  of  a  hot  oven,  so  that 
if  air  is  entangled  in  a  mass  of  dough,  it  gives 
a  certain  lightness  when  the  whole  is  baked.  This 
is  the  cause  of  the  sponginess  of  cakes  made  with 
eggs.  The  viscous  albumen  catches  the  air  and 
holds  it,  even  when  it  is  expanded,  unless  the 
oven  is  too  hot,  when  the  sudden  expansion  is 
liable  to  burst  the  bubbles  and  the  cake  falls. 

As  has  been  said,  the  production  of  the  porous 
condition,  by  means  of  carbonic  acid,  generated  in 
some  other  way  than  by  the  decomposition  of 
starch,  was  the  study  of  practical-  chemists  for 
some  years.  Among  the  first  methods  proposed, 
was  one  undoubtedly  the  best  theoretically,  but 
very  difficult  to  put  in  practice,  viz.,  the  liberation 
of  carbonic  acid  gas  from  bi-carbonate  of  sodium, 
by  means  of  muriatic  acid. 

I  1  iv  11  11 

Na  H  C  03   +   H  CI  = 

Soda.  Hydrochloric 
Acid. 

II  I    II  IV 

=  Na  CI   -f-  H2  O   +  C  Oa 


32 


THE  CHEMISTRY  OF 


The  difficulty  lies  in  the  fact  that  this  libera- 
tion of  gas  is  instantaneous  on  the  contact  of  the 
acid  with  the  soda,  and  only  a  skilled  hand  can 
mix  the  bread  and  place  it  in  the  oven  without 
the  loss  of  much  of  the  gas.  Tartaric  acid  (the 
acid  phosphates),  sour  milk  (lactic  acid),  vinegar 
(acetic  acid),  alum,  all  of  which  have  been  used, 
are  open  to  the  same  objection.  Cream  of  tartar 
is  the  only  acid  substance  commonly  used  which 
does  not  liberate  the  gas  by  simple  contact  in 
the  cold.  It  unites  with  soda  only  when  heated, 
because  it  is  very  slightly  soluble  in  cold  water. 
For  the  even  distribution  of  the  gas  by  thorough 
mixing,  cream  of  tartar  would  seem  to  be  the 
best.  The  chemical  reaction  is  shown  in  the  table 
on  page  But  as,  beside  gas,  there  are  other 

products  which  remain  behind  in  the  bread,  in 
the  case  of  all  the  so-called  baking  powders, 
the  healthfulness  of  these  residues  must  be  con- 
sidered. 

Common  salt,  the  residue  from  the  first-men- 
tioned reaction,  is  the  safest,  and  perhaps  the 
residues  from   acid  phosphate  are  next  in  order. 


COOKING  AND  CLEANING.  33 


The  tartrate,  lactate,  and  acetate  of  sodium  are 
not  known  to  be  especially  hurtful.  As  the  im- 
portant constituent  of  Seidlitz  powders  is  Rochelle 
salt,  the  same  compound  as  that  resulting  from  the 
use  of  cream  of  tartar  and  soda,  it  is  not  likely 
to  be  very  deleterious,  taken  in  the  small  quantities 
in  which  even  habitual  "  soda-biscuit "  eaters  take 
it. 

The  various  products  formed  by  the  chemical 
decomposition  of  alum  and  soda  are  possibly  the 
most  injurious,  as  the  sulphates  are  supposed  to 
be  the  least  readily  absorbed  salts.  Taking  into 
consideration  the  advantage  given  by  the  insolubility 
of  cream  of  tartar  in  cold  water,  and  the  com- 
paratively little  danger  from  its  derivative,  Rochelle 
salt,  it  would  seem  to  be,  on  the  whole,  the  best 
substance  to  add  to  the  soda  in  order  to  liberate 
the  gas ;  but  the  proportions  must  be  chemically 
exact,  according  to  the  reaction  given.  At  least, 
there  must  be  no  alkali  left,  for  a  reason  which 
will  be  given  under  the  head  of  hindrances  to 
digestion. 

Hence,    baking    powders   prepared     by  weight 


34 


THE  CHEMISTRY  OF 


and  carefully  mixed,  are  a  great  improvement  on 
the  teaspoonful  measured  by  guess.  The  reactions 
of  the  various  baking  powders  with  the  proportions 
of  each  will  be  given  on  page 

Another  group  of  substances  which,  by  their  slow 
combustion  or  oxidation  in  the  animal  body,  yield 
carbonic  acid  gas  and  water,  and  furnish  heat  to 
the  system,  comprises  the  animal  fats :  as,  for 
instance  —  suet,  lard  and  butter;  and  the  vegetable 
oils,  as  olive  oil,  the  oily  matter  in  corn,  oats,  etc. 

These  fatty  materials  all  have  a  similar  compo- 
sition, containing  when  pure  only  carbon,  hydrogen, 
and  oxygen.  They  differ  from  starch  and  sugar 
in  the  proportion  of  oxygen  to  the  carbon  and 
hydrogen,  there  being  very  little  oxygen  relatively 
in  the  fatty  group,  hence  more  must  be  taken  from 
the  air  for  their  combustion. 

Ci8  H36  O2  C6  H10  O5 

Stearine  in  Suet.  Starch. 

One  pound  of  starch  requires  one  and  two-tenths 
pounds  of  oxygen,  while  one  pound  of  suet  requires 
about  three  pounds  of  oxygen  for  perfect  combus- 
tion.   At  the  same  time,  a  greater  quantity  of  heat 


COOKING  AND  CLEANING.  35 


can  be  obtained  from  the  fats,  pound  for  pound, 
than  from  starch  or  sugar;  hence,  people  in  Arctic 
regions  require  fat. 

A  most  noticeable  difference  between  the  starch 
group  and  the  fat  group,  is  that  the  latter  is  stored 
up  in  the  system  against  a  time  of  need.  This  is 
the  more  easily  done,  since  the  fats  do  not  seem 
to  undergo  any  essential  change  in  order  that  they 
may  be  absorbed.  They  pass  the  mouth  and  stomach 
without  any  chemical  change,  and  only  when  they 
encounter  the  bile  and  the  other  intestinal  juices, 
is  there  any  question  as  to  what  happens. 

With  these  fluids,  the  bile  especially,  the  fats 
form  emulsions  in  which  the  globules  are  finely 
divided  and  rendered  capable  of  passing  through 
the  membranes  into  the  circulatory  system.  The 
change,  if  any,  is  not  one  destructive  of  the  proper- 
ties of  the  fatty  matters.  The  globules  are  carried 
along  by  the  blood,  and  deposited  wherever  needed, 
to  fill  up  the  spaces  in  the  muscular  tissue,  and 
to  serve  as  a  reserve  supply  of  fuel. 

There  seems  to  be  good  reason  for  believing 
that  the   animal  does   derive  some  fat  from  the 


36     THte  CHEMISTRY  OF  COOKING,  ETC. 


other  constituents  of  its  food,  but  it  is  not  an 
important  question  in  the  diet  of  mankind,  for 
even  the  rice  eaters  use  butter  or  oil  with  their 
food. 

It  must  not  be  inferred  from  what  has  been  said 
that  the  oxidation  of  starch  and  fat  is  the  only 
source  of  heat  in  the  animal  body.  A  certain 
quantity  is  undoubtedly  derived  from  the  chemical 
changes  of  the  other  portions  of  food,  but  the 
chemistry  of  these  changes  is  not  yet  fully  under- 
stood. 


CHAPTER  III. 


NITROGENOUS  FOOD  AND  THE  CHEMISTRY  OF  NUTRITION. 

JN  the  previous  chapter,  the  food  necessary  for 
the  existence  of  the  adult  animal  was  con- 
sidered ;  but  animals  do  more  than  exist,  they 
move  and  exert  force,  in  mechanical  terms  they 
do  work  •  also  the  young  animal  grows. 

For  growth  and  work,  something  else  is  needed 
beside  starch  and  fat.  The  muscles  are  the  in- 
struments of  motion  and  they  must  grow  and  be 
nourished,  in  order  that  they  may  have  power. 
The  nourishment  is  carried  to  them  by  the  blood 
corpuscles.  We  find  in  these,  as  well  as  in  mus- 
cular tissue,  an  element  which  we  have  not  here- 
tofore considered,  nitrogen.  We  find  it  also  in  the 
products  of  their  decomposition,  hence  we  reason 

37 


38 


THE  CHEMISTRY  OF 


that  if  the  wear  and  tear  of  the  muscles  causes 
the  liberation  of  nitrogenous  compounds,  which 
pass  out  of  the  system  as  such,  this  loss  must 
be  supplied  by  the  use  of  some  kind  of  food 
which  contains  nitrogen.  Starch  and  fat  do  not; 
therefore  they  cannot  furnish  it  to  the  blood. 

The  typical  food  of  this  class  is  albumen,  white 
of  egg ;  hence  the  terms  albuminous  and  albuminoid 
are  often  used  as  descriptive  of  the  group.  The 
other  common  articles  of  diet  containing  nitrogen 
are  the  casein  of  milk,  the  musculine  of  animal 
flesh,  the  gluten  of  wheat,  and  the  legumen  of 
peas  and  beans.  The  proportion  of  the  element 
in  each  is  shown  in  the  table  on  page  53. 

The  chemical  changes  which  these  bodies  un- 
dergo are  not  well  understood.  The  nitrogenous 
food  is  finely  comminuted  in  the  mouth,  because, 
as  before  stated,  chemical  action  is  rapid  in  pro- 
portion to  the  fineness  of  division ;  but  it  is  in 
the  stomach  that  the  first  chemical  change  occurs. 

The  agents  of  this  change  are  the  pepsin  and 
the  acid  of  the  gastric  juice ;  the  two  together 
render  the  nitrogenous  substance  soluble  and  dia- 


COOKING  AND  CLEANING.  39 


lysable,  capable  of  passing  through  the  membranes. 
Neither  seems  able  to  do  this  alone,  and  it 
does  not  seem  to  matter  what  acid  is  present  so 
long  as  it  is  acid  and  just  acid  enough  ;  but  if  the 
acid  is  neutralized,  action  ceases ;  hence  the  danger 
of  soda  biscuit  with  too  much  soda. 

The  chemical  changes  which  go  on  after  the 
albumen  is  taken  into  the  system  are  not  known. 
A  decomposition  of  some  sort  takes  place,  and  the 
nitrogen  passes  out  of  the  system  in  urea,  being 
separated  by  the  kidneys,  as  carbonic  acid  gas  is 
by  the  lungs. 

The  effect  of  cooking  upon  nitrogenous  food 
should  be  such  as  will  render  the  substance  more 
soluble,  because  in  this  case  digestibility  means 
solubility.  Therefore  white  of  egg  (albumen)  and 
curd  of  milk  (casein),  when  hardened  by  heat, 
must  not  be  swallowed  in  lumps. 

In  the  case  of  flesh,  the  cooking  should  soften 
and  loosen  the  connecting  tissue,  so  that  the  little 
bundles  of  fibre,  which  contain  the  nutriment,  may  ^ 
fall  apart  easily  when  brought  in  contact  with  the 
teeth.     Any  process  which  toughens  and  hardens 


40 


THE  CHEMISTRY  OF 


the  meat  should  be  avoided.  The  cooking  of 
beans  and  all  leguminous  vegetables  should  soften 
and  loosen  the  compact  grains.  Hard  water  should 
be  avoided,  as  an  insoluble  lime  or  magnesia  com- 
pound of  legumen  is  formed. 

We  have  now  considered  the  three  classes  of 
food  under  one  or  more  of  which  all  staple  articles 
of  diet  may  be  placed — the  starch  food,  the  fats  and 
the  nitrogenous  material.  Some  general  principles  of 
diet,  indicated  by  science,  remain  to  be  discussed. 

One  of  the  most  obvious  questions  is  :  Which  is 
best, — starch  or  fat,  beans  and  peas,  or  flesh? 
As  to  starch  or  fat,  the  question  has  been  answered 
by  experience,  and  science  has  only  tried  to  explain 
the  reason.  The  colder  the  climate  the  more  fat 
the  people  eat.  The  tropical  nations  live  chiefly 
on  starch  foods,  as  rice.  From  the  statements  on 
page  50,  it  will  be  seen  that  this  is  right ;  fat  yields 
more  heat  than  rice.  Therefore  the  inference  is 
plain  that  in  the  cold  of  winter  fat  is  appropriate 
food,  while  in  the  heat  of  summer  rice  or  some 
other  starch  food  should  be  substituted. 

No  such  evident  rule  can  be  seen  in  the  case 


COOKING  AND  CLEANING.  41 


of  the  albuminous  foods.  At  most,  the  class  can 
be  divided  into  three  groups.  The  first  includes 
the  material  of  vegetable  origin,  as  peas,  lentils, 
and  the  gluten  of  wheat.  The  second  comprises 
the  white  of  egg  and  the  curd  of  milk,  material  of 
animal  origin.  The  third  takes  in  all  the  animal 
flesh  used  by  mankind  as  food. 

Considering  the  question  from  a  purely  chemical 
standpoint,  without  regarding  the  moral  or  social 
aspects  of  the  case,  two  points  stand  out  clearly : 
ist.  If  the  stored-up  vegetable  matter  has  required 
the  force  derived  from  the  sun  to  prepare  it,  the 
tearing  apart,  and  giving  back  to  the  air  and  earth, 
the  elements  of  which  it  was  built  up,  will  yield 
so  much  force  to  whatever  tears  it  down ;  but  a 
certain  amount  of  energy  must  be  used  up  in 
this  destruction.  2nd.  If  the  animal,  having  accom- 
plished this  decomposition  of  the  vegetable,  and 
appropriated  the  material,  is  killed,  and  the  pre- 
pared nitrogenous  food  in  the  form  of  muscle  is 
eaten  by  man,  then  no  force  is  necessary  to  render 
the  food  assimilable ;  it  is  only  to  be  dissolved 
in  order  that  it  may  enter  into  the  circulation. 


42 


THE  CHE  MIS  TR  T  OF 


The  force-producing  power  is  not  lost ;  it  is 
only  transferred  to  another  animal  body.  Hence 
the  ox  or  the  sheep  can  do  a  part  of  man's 
work  for  him  in  preparing  the  vegetable  food  for 
use,  and  man  may  thus  accomplish  more  than  he 
otherwise  could.  There  is,  however,  another  side 
to  this  question.  Nearly  all,  if  not  all,  young 
animals  live  on  food  of  animal  origin.  The  young 
of  the  human  race  live  on  milk,  but  it  has  been 
found  by  experience  that  milk  is  not  the  best 
food  for  the  adult  to  live  upon  to  the  exclusion 
of  all  else.  It  is  not  conducive  to  quickness  of 
thought  or  general  bodily  activity. 

This  fact,  with  many  others,  leads  us  to  the 
conclusion  that  mankind  needs  some  vegetable 
food.  Two  other  facts  sustain  this  inference.  The 
digestive  organs  of  the  herbivorous  animals  form 
fifteen  to  twenty  per  cent,  of  the  whole  weight 
of  the  body.  Those  of  the  carnivorous  animals 
form  five  to  six  per  cent.,  those  of  the  human 
race  about  eight  per  cent.  The  length  of  the 
canal  through  which  the  food  passes  bears  about 
the  same  relation  in  the  three  classes.     A  mixed 


COOKING  AND  CLEANING.  43 


diet  seems  to  be  indicated  as  desirable  by  every 
test  which  has  been  applied,  but  the  proportions 
in  which  the  vegetable  and  animal  food  are  to  be 
mingled,  as  well  as  the  relative  quantities  of  car- 
bonaceous and  nitrogenous  material  which  will  give 
the  best  efficiency  to  the  human  machine  are  not 
so  easily  determined. 

Dietaries,  based  upon  experience  and  chemical 
analysis,  have  been  prepared  for  soldiers'  rations, 
and  for  use  in  prisons.  Many  cook-books  and 
most  works  on  physiology  give  lists  of  quantities. 

One  who  has  studied  the  question  for  years 
says :  "  Not  only  the  age  and  occupation,  but 
also  the  individuality  of  the  person  play  an  im- 
portant part  in  the  regulation  of  diet,  and  decide 
not  only  the  quantity  but  also  the  kind  of  the 
food,  and  the  form  in  which  it  is  to  be  taken  .  . 
For  the  proper  assimilation  of  the  nourishment  and 
its  complete  effect  in  the  organism,  the  food  must 
be  agreeable ;  it  must  relish  .  .  A  supply  of 
needful  nourishment  is  not  enough.  Man  requires 
yet  more.  He  must  find  his  food  pleasing  to  the 
taste    .    .    The     boiling    and    roasting    of  food 


44 


THE  CHE  MIS  TR  T  OF 


materials  are  operations  which  we  find  only  among 
civilized  people,  and  they  have  been  developed 
with  the  advance  of  civilization.  The  whole  art 
of  cooking  amounts  to  this :  So  to  prepare  the 
food  that  it  will  best  answer  its  end."* 

The  nutrition  of  the  animal  body,  that  is,  the 
assimilation  of  the  food  taken,  is  dependent  upon 
absorption.  Absorption  is  dependent  upon  pre- 
vious chemical  processes.  These  processes  are 
contingent  upon  the  secretions,  the  saliva,  the 
gastric  juice,  etc. ;  and  it  is  a  well-known  fact 
that  the  flow  of  these  liquids  is,  lo  a  great  ex- 
tent, under  the  control  of  the  nerves.  Whatever 
excites  the  nerves  pleasantly,  causes  an  abundant 
secretion  of  the  chemical  agents  of  food  change. 
In  this  fact  lies  the  secret  of  modern  cooking,  the 
judicious  use  of  condiments. 

Pettenkofer  (Konig,  page  21)  says  of  condi- 
ments :  "  I  may  compare  them  to  the  right  use 
of  lubricants  for  an  engine,  which  indeed  cannot 
replace  the   steam   power,    but  may  help  it  to  a 

*  Die  menschlichen  Nahrungs-und  Genussmittel,  von  Dr.  J.  Konig. 
Berlin,  1880.  100. 


COOKING  AND  CLEANING. 


45 


much  easier  and  more  regular  action,  and  besides, 
prevent  quite  naturally  the  wearing  out  of  the 
machine.  In  order  to  be  able  to  do  this,  one 
condition  is  absolutely  essential :  the  lubricant  must 
not  attack  the  machine,  it  must  be  harmless  " 

Cooking  has  thus  become  an  art  worthy  the 
attention  of  intelligent  and  learned  women.  The 
laws  of  chemical  action  are  founded  upon  the  law 
of  definite  proportions,  and  whatever  is  added 
more  than  enough,  is  in  the  way.  The  head  of 
every  household  should  study  the  condition  of  her 
family,  and  tempt  them  with  dainty  dishes  if  that 
is  what  they  need.  If  the  ashes  have  accumulated 
in  the  grate,  she  will  call"  a  servant  to  shake  them 
out  so  that  the  fire  may  burn.  If  she  sees  that 
the  ashes  of  the  food  previously  taken  are  clog- 
ging the  vital  energy  of  her  child,  she  will  send 
him  out  into  the  air,  with  oxygen  and  exercise  to 
make  him  happy,  but  she  will  not  give  him  more 
food. 

Nature  seems  to  have  made  provision  for  the 
excess  of  heat,  resulting  from  the  oxidation  of 
too  much  starch    or  fat,  by  the  ready  means  of 


46 


THE  CHEMISTRY  OF 


evaporation  of  water  from  the  surface,  this  loss  of 
water  being  supplied  by  drinking  in  a  fresh  sup- 
ply, which  goes,  without  change,  into  the  circu- 
lation. The  greater  the  heat,  the  greater  the 
evaporation ;  hence  the  importance  of  water  as  an 
article  of  diet  must  not  be  overlooked.  For  an 
active  person,  the  supply  has  been  estimated  at 
three  quarts  per  day.  Water  is  the  heat  regulator 
of  the  animal  body. 

While  dangerous  disease  seldom  seems  to  result 
from  eating  an  excess  of  starch  or  fat,  because 
the  portion  not  wanted  is  rejected  as  so  much 
sand,  many  of  the  most  complicated  disorders 
do  result  from  an  excess  of  nitrogen  diet. 

The  readiness  with  which  such  substances  undergo 
putrefaction,  and  the  many  noxious  products  to 
which  such  changes  give  rise,  should  lead  us  to 
be  more  careful  as  to  the  quantity  of  food. 

A  growing  person  needs  about  one  part  of 
nitrogenous  food  to  four  of  starch  and  fat;  a  grown 
person,  one  part  nitrogenous  food  to  five  or  six 
of  starch  and  fat.  A  fair  average  ration  per  day 
is  perhaps : 


COOKING  AND  CLEANING.  47 


Bread 


i  lb.  10  oz. 


Fat 


to  2  OZ. 


Rice  (cooked) 


Flesh 


h  lb. 
h  lb. 


All  processes  of  cooking  and  the  use  of  all  con- 
diments which  hinder  digestion  should  be  avoided. 
Woody  fibre  or  cellulose,  as  bran,  irritates  the 
digestive  canal,  and  causes  it  to  empty  itself  of 
the  food  before  the  chemical  change  is  complete. 
An  excess  of  sugar  sometimes  decomposes  with 
the  formation  of  acids  which  have  the  same  effect. 

Tannin,  tobacco,  salt  in  excess,  and  alcohol,  all 
harden  the  albuminous  part  of  the  food,  and  by 
this  means  hinder  solution. 

Certain  substances,  as  alcohol  and  coffee,  lessen 
the  amount  of  food  needed  for  the  time  being. 

The  fats 'all  decompose  at  about  3000  F.,  into 
various  bodies,  some  of  them  exceedingly  acrid 
and  irritating  to  the  mucous  membrane  of  the  nose 
and  throat,  and  which  must  also  prove  offensive 
to  the  lining  of  the  stomach.  This  is  probably  the 
reason  why  many  people  cannot  bear  food  fried 
in  fat,  • 


48 


THE  CHEMISTRY  OF 


In  counting  the  cost  of  the  several  articles  of 
diet,  not  only  the  price  per  pound,  but  the  digesti- 
bility must  be  taken  into  account. 

It  has  been  found  by  experiment  that  of  the 
total  starch  in  rice  less  than  one  per  cent,  is 
rejected,  while  in  potatoes  nearly  eight  per  cent,  is 
not  used.    (See  table,  page  52). 

The  cost  of  a  diet  which  derives  all  the  nitrogen 
from  the  animal  kingdom  has  been  estimated  in 
Germany  as  9.2  marks  per  day;  while  an  entire 
vegetable  diet,  giving  the  same  chemical  con- 
struction, is  given  at  1.95  marks  per  day.  This 
is  a  very  evident  reason  why  the  working  people 
of  all  lands  (except  America)  live  on  vegetable 
food  almost  entirely. 


COOKING  AND  CLEANING. 


49 


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THE  CHEMISTRY  OF 


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COOKING  AND  CLEANING. 


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52 


THE  C  HEM  IS  TR  T  OF 


Digestibility  of  some  articles  of  food  shown 
by  the  per  cent,  of  the  several  constituents  re- 
jected : 


Nitrogen. 

Fat. 

Starch  Matter. 

Maize 

15-5 

17-5 

3-2 

Rice 

20.4 

7-i 

•9 

Potatoes 

32.2 

3-7 

7.6 

Macaroni 

17.I 

5-7 

1.2 

Yellow  Beets 

39-o 

6.4 

18.2 

White  Bread 

18.7 

.8 

Roast  Meat 

2-5 

21. 1 

Eggs 

2.9 

5-o 

Milk 

7.0 

7.i 

Butter 

"•3 

2.7 

Bacon 

12. 1 

17.4 

It  has  been  estimated  (Moleschott)  that  a  work- 
ing man  needs  daily  130  grms.*  of  nitrogenous 
food  and  448  grms.  of  non-nitrogenous  food,  starch, 
fat,  etc. 

The  following  table  shows  the  weights  of  the 
different  kinds  of  food  which  must  be  eaten  in 
order  that  the  required  quantity  may  be  obtained : 


*  28  grms.  =  1  ounce  nearly. 


COOKING  AND  CLEANING. 


For 
130  grms. 
Nitrogenous 


Substances. 

Cheese  33® 

Lentils  491 

Peas  582 
Beans  "  Acker- 

bohnen "  590 

Ox  Flesh  614 

Eggs  968 

White  Bread  1,444 

Corn      "  1,642 

Rice  2,562 

Rye  Bread  2,875 

Potatoes  10,000 


For 

448  grms. 
Non-nitrogenous 
Substances. 


Rice  572 

Maize  625 

White  Bread  631 

Lentils  806 

Peas  819 
Beans  "  Acker- 

bohnen "  823 

Eggs  902 

Rye  Bread  930 

Cheese  2,011 

Potatoes  2,039 

Ox  Flesh  2,261 


Daily  Rations  in  grms. 

Albuminous 

[(nitrogenous)  Starch  Mineral 

Food.  Fat.     Food.       Salts.  Water. 

Soldier's  Ration 

(ordinary)               119  56  485 
Soldier's  Ration 

(very  rich)              116  209  40° 

Working  Men             148  87      526       30  2858 


(Mean  of  estimates  by  12  different  authorities.) 


54     THE  CHEMISTRY  OF  COOKING,  ETC. 


The  daily  need  of  a  woman  is  counted  as 
three-fourths  or  four-fifths  that  of  a  man. 

Elementary  Composition  in 


#  of  C.  H. 

0. 

N.  S. 

Vegetable  Albumen     c^.i  7.2 

20.5 

17.6  T.6 

Egg               "          534  7-o 

22.4 

15.7  1.6 

Flesh  (Fowl)              53.18  7.03 

.48 

15-75  i-56 

Casein  (Curd  of  Milk)  53.5  7.05 

.88 

15.77  -8 

Of  100  parts  of  food  (solid 

and  liquid)  taken, 

is  discharged  : 

By  the  Intestines 

6.7 

per  cent. 

"     "  Kidneys 

49-3 

(<  (< 

"     "   Skin  and  Lungs 

42.6 

<<  <( 

PART  II. 


CHAPTER  I. 

THE  CHEMISTRY  OF  CLEANING. 

^^"EXT  to  the  materials  for  food,  those  used  for 
the  very  necessary  operations  of  cleaning  are 
perhaps  of  greatest  interest  to  the  housekeeper. 

This  chapter  will  discuss  the  properties  of  the 
chemical  substances  which  are  suited  to  aid  in 
performing  the  work  of  cleansing  to  the  best 
advantage. 

First  in  importance  among  these  chemical  ma- 
terials are  soap  and  its  substitutes. 

"  Whether  the  extended  use  of  soap  be  preceded 
or  succeeded  by  an  improvement  in  any  com- 
munity—  whether  it  be  the  precursor  or  the  result 
of  a  higher  degree    of   refinement   amongst  the 

55 


50 


THE  CHE  MIS  TR  T  OF 


nations  of  the  earth  —  the  remark  of  Liebig  must 
be  acknowledged  to  be  true,  that  the  quantity  of 
soap  consumed  by  a  nation  would  be  no  inaccurate 
measure  whereby  to  estimate  its  wealth  and  civiliza- 
tion. Of  two  countries  with  an  equal  amount  of 
population,  the  wealthiest  and  most  highly  civilized 
will  consume  the  greatest  weight  of  soap.  This 
consumption  does  not  subserve  sensual  gratification, 
nor  depend  upon  fashion,  but  upon  the  feeling  of 
the  beauty,  comfort  and  welfare  attendant  upon 
cleanliness ;  and  a  regard  to  this  feeling  is  coin- 
cident with  wealth  and  civilization."  * 

It  is  surely  a  problem  of  the  greatest  interest  to 
every  housekeeper,  how  to  keep  her  household 
and  its  belongings  in  a  state  of  cleanliness  that 
shall  be  a  state  of  perfect  health ;  for  a  large 
portion  of  disease  is  a  direct  result  of  uncleanly 
ways.  [The  toleration  of  impure  air  in  close  rooms 
is  one  of  the  most  common,  as  well  as  one  of  the 
most  easily  remedied  of  these  uncleanly  ways.] 

This  state  of  cleanness  must  also  be  attained 
at  the  least  cost  in  money,  time  and  labor.  Such 

*  Muspratt's  Chemistry  as  applied  to  Arts  and  Manufactures.^ 


COOKING  AND  CLEANING.  57 


a  question  ought  to  stir  the  business  capacity  of 
every  woman  in  charge  of  a  house.  As  we  have 
said,  soap  and  its  substitutes  justly  claim,  first 
of  all,  our  attention. 

Many  primitive  peoples  find  a  substitute  for  soap 
in  the  roots,  bark  or  fruit  of  certain  plants.  Nearly 
every  country  is  known  to  produce  such  vegetable 
soaps,  the  quality  which  they  possess  of  forming 
an  emulsion  with  oily  substances  being  due  to  a 
peculiar  vegetable  substance,  known  as  Saponin. 
Many  of  these  saponaceous  barks  and  fruits  are 
now  used  with  good  results  —  the  "soap  bark" 
of  the  druggist  being  one  of  the  best  substances 
for  dressing  over  black  dress  goods,  whether  of 
silk  or  woollen. 

The  fruit  of  the  Soapberry  tree  —  Papindus 
Saponaria  —  a  native  of  the  West  Indies,  is  said 
to  be  capable  of  cleansing  as  much  linen  as  sixty 
times  its  weight  of  soap. 

Wood  ashes  were  probably  used  as  cleansing 
material  long  before  soap  was  made,  as  well  as 
long  after  its  general  use.  Their  properties  and 
value  will  be  considered  later. 


58 


THE  CHEMISTRY  OF 


Soaps  for  laundry  use  are  chiefly  composed  of 
alkaline  bases,  combined  with  fatty  acids.  Their 
action  is  "gently  but  efficiently  to  dispose  the 
greasy  dirt  of  the  clothes  and  oily  exudations  of 
the  skin  to  miscibility  with,  and  solubility  in  wash 
water."  * 

We  may  state  it  in  this  way.  All  kinds  of 
cleansing,  whether  it  be  of  our  skins,  our  clothes, 
our  painted  wood-work,  our  windows  or  our  dishes, 
consist  of  two  distinct  operations  :  first,  the  solu- 
tion or  emulsion  of  the  oily  matter  which  causes 
the  dust  and  dirt  to  adhere  ;  second,  the  mechan- 
ical removal  of  the  dust  and  dirt,  which,  in  most 
cases,  is  effected  by  water.  Sometimes,  as  in  the 
case  of  silver  and  paint,  the  cleansing  agent  is 
fine  sand  or  chalk. 

It  will  readily  be  seen  that  the  first  operation — 
the  removal  of  the  oily  matter — is  of  prime  im- 
portance in  the  laundry.  In  order  clearly  to 
understand  the  question  of  the  best  means  to 
secure  this   removal,  we    must   first  consider  the 

*   Chemistry   applied   to   the   Manufacture    of    Soaps  and  Candles. 
Morfit. 


COOKING  AND  CLEANING. 


59 


properties  of  the  grease  and  oily  matters,  and  next, 
what  agents  will  dissolve  them  or  form  an  emulsion 
with  them. 

Oily  matters  in  general  are  soluble  in  certain 
substances,  as  salt  is  soluble  in  water,  and  can  be 
recovered  in  their  original  form  from  such  solutions 
by  simple  evaporation.  Some  of  them  readily 
combine  with  alkalies  to  form  the  kind  of  com- 
pound which  we  call  soap.  Others  in  contact  with 
the  alkalies  form  emulsions,  so-called,  in  which  the 
fatty  globules  are  suspended,  forming  an  opaque 
liquid.  These  emulsions  are  capable  of  being  in- 
definitely diluted  with  clear  water,  and  by  this  means 
the  fatty  globules  are  all  carried  away.  The  opacity 
of  soap-suds  is  due  to  the  fact  that  it  contains 
particles  in  suspension,  the  nature  of  which  will  be 
presently  shown. 

Setting  aside  the  vegetable  saponin,  we  have 
then  two  classes  of  agents  which  affect  oily  mat- 
ters,— the  one  class  by  simple  solution,  as  turpen- 
tine, alcohol,  ether,  benzine,  etc. ;  the  other  class 
by  a  direct  union,  or  by  the  formation  of  an 
emulsion.    Agents  of  the  latter  class  are  substances 


60 


THE  CHEMISTRY  OF 


known  in  chemistry  as  the  alkali  metals,  and  in 
order  to  justify  the  somewhat  extended  discussion 
of  these  alkali  metals,  we  must  remind  our  readers 
that  the  value  of  all  soaps  as  detergents  depends 
upon  the  alkali  chiefly.  To  the  distinguished 
French  chemist,  Chevreul,  is  due  our  knowledge 
of  the  action  of  soaps. 

"The  neutral  salts  formed  by  the  alkalies  and  the 
fat  acids  are  decomposed  by  the  water,  whereby 
insoluble  double  fat  acid  salts,  —  stearates,  palmi- 
tates,  oleates — are  separated,  while  the  alkali  is 
set  free.  By  means  of  the  free  alkali  the  im- 
purities clinging  to  the  materials  are  removed." 

Every  woman  must  have  noticed  the  peculiar 
opaque  appearance  of  soap-suds,  even  before  any- 
thing has  been  washed  in  it.  This  is  due  to  the 
suspension  in  the  water  of  the  particles  of  these 
"insoluble  double  fat  acid  salts." 

[Hot  water  will  dissolve  soaps  without  this  de- 
composition, but  on  cooling  the  separation  takes 
place.] 

As  each  soap-maker  claims  that  his  product 
contains  something  which   renders  it   better  than 


COOKING  AND  CLEANING.  61 


other  soaps,  or  different  from  them,  and  as  the 
chief  stress  in  his  recommendation  rests  on  the 
fatty  matters  used,  "  Oil  soap  is  superior  to  resin 
soap,"  and  the  like,  it  behooves  the  housekeeper 
to  remember  that,  within  certain  limits  of  course, 
the  kind  of  fatty  acid  does  not  so  much  matter 
to  her  (provided  only  that  it  is  not  putrid  or 
otherwise  unfit  for  use)  as  the  quantity  and  quality 
of  the  alkali,  and  as  she  is  often  called  upon  to 
believe  that  some  new  chemical  has  just  been 
discovered  which  makes  a  far  more  efficient  soap 
than  the  world  has  ever  before  seen,  it  may  be 
instructive  for  her  to  follow  our  discussions  of  the 
alkali  metals  and  their  compounds. 

The  chemical  group  of  "  alkali  metals "  com- 
prises six  substances — Ammonium,  Cassium,  Lithium, 
Potassium,  Rubidium  and  Sodium.  Two  of  the 
six — Cassium  and  Rubidium  —  were  discovered  by 
means  of  the  spectroscope,  not  many  years  ago,  in 
the  mineral  waters  of  Durckheim,  and  probably 
the  total  amount  for  sale  of  all  the  salts  of  these 
metals,  could  be  carried  in  one's  pocket.  A  third 
alkali  metal  —  Lithium  —  occurs  in  several  minerals, 


62 


THE  CHEMISTRY  OF 


and  its  salts  are  of  frequent  use  in  the  laboratory, 
but  it  is  not  sufficiently  abundant  to  be  of  com- 
mercial importance. 

As  regards  the  three  remaining  alkali  metals,  the 
i      i  ii 

oxide  of  Ammonium,  (NH4)HO,  is  known  as  "Vola- 

i  I  ii 

tile  Alkali,"  the  oxides  of  Potassium,  KHO,  and 
i  i  ii 

Sodium,  NaHO,  as  "  Caustic  Alkalies."  With  these 
three  alkalies  and  their  compounds,  and  these  alone, 
are  we  concerned  in  housekeeping.  The  volatile 
alkali,  Ammonia,  has  been  recently  prepared  in  quan- 
tity and  price  such  that  every  housekeeper  may 
become  acquainted  with  its  use.  It  does  not  often 
occur  in  soaps,  and  its  use  is  confined  to  the  more 
delicate  cleansing  operations,  the  bath,  the  washing 
of  woollens,  and  other  cases  where  its  property  of 
evaporating,  without  leaving  any  residue  to  attack  the 
fabric  or  to  attract  anything  from  the  air,  is  invaluable. 
This  property  affords  a  safeguard  against  the  care- 
lessness of  the  laundress  in  not  sufficiently  rinsing 
the  fabric,  and  this  imperfect  rinsing  is  at  the  bottom 
of  most  of  the  trouble  in  washing  woollens  with 
soap  or  caustic  alkali.    All  flannels  worn  next  the 


COOKING  AND  CLEANING.  63 


skin,  all  the  woollens  of  an  infant's  wardrobe,  should 
be  washed  in  water  made  soft  and  alkaline  by 
ammonia,  or  ammonium  carbonate.  An  additional 
advantage  will  be  found  in  the  fact  that  the  shrink- 
age of  woollens  thus  washed  is  very  slight.  The 
ammonium  compounds  are  somewhat  more  ex- 
pensive  than  the  caustic  alkalies,  but  in  the  present 
time,  when  an  ammoniacal  liquor  is  largely  produced 
as  a  secondary  product  in  the  manufacture  of  coal 
gas,  the  cost  is  not  excessive  compared  with  the 
benefit  its  use  confers.  For  use  in  the  bath,  and 
for  woollens,  the  ammoniacal  gas  liquor  must  have 
passed  through  a  process  of  purification,  in  order 
to  free  it  from  some  other  products  of  the  de- 
structive distillation  of  coal,  which  is  not  healthful 
or  useful.  This  caution  must  be  borne  in  mind, 
as  a  crude  article  is  sometimes  sold  for  cleaning 
paint  or  carpets ;  this  is  not  fit  for  the  uses  we 
have  been  specifying. 

Ammonia  water,  bought  of  the  best  dealers  in 
chemicals  and  druggists'  supplies,  costs  about  30 
cents  a  pint,  without  the  bottle. 

A  pint  of  this  liquid  possesses  as  much  alkaline 


64 


THE  CHEMISTRY  OF 


I  IV  II  I  II 

value  as  ten  ounces  of  sal  soda,  Na2C03+  ioH20, 
and  has  not  the  injurious  properties  of  the  latter, 
even  when  used  in  excess.  As  the  alkali  is  volatile, 
and  water  nearly  boiling  will  retain  only  about  one- 
seventh  as  much  of  the  ammonia  gas  as  water  at 
the  ordinary  temperature  of  the  air,  it  will  be  seen 
that  the  directions  on  the  various  bottles  of 
"  Magical  "  washing  fluids  which  contain  ammonia, 
to  pour  the  required  quantity  into  hot  water,  with 
the  word  "hot"  especially  emphasized,  are  at 
variance  with  the  known  properties  of  this  sub- 
stance. The  fluid  should  be  largely  diluted  with 
cold  water,  and  then  added  to  the  warm  water, 
never  to  water  too  hot  to  bear  the  hand  in. 

Ammonia  is  most  excellent  for  cleaning  glass 
(but  not  for  brass,  as  it  dissolves  copper,  and 
copper  salts) . 

A  teaspoonful  of  ammonia,  added  to  a  quart 
of  water,  is  the  best  possible  agent  for  cleansing 
hair  brushes. 

For  use  in  travelling,  the  solid  ammonium  car- 
bonate is  preferable ;   for  use  in  hard  water  it  is 


COOKING  AND  CLEANING.  65 


also  better,  as  the  lime  is  precipitated  out  by  it  as 
by  sal  soda.  It  costs  twenty-five  or  thirty  cents 
a  pound,  and  one  pound  of  it  is  of  as  much 
alkaline  value  as  two  pounds  of  sal  soda. 

The  compounds  of  the  two  alkali  metals,  Potas- 
sium and  Sodium,  are  capable  of  saponifying  fats 
and  forming  the  complex  substances  known  as 
soaps. 

For  the  compounds  of  these  alkalies,  employed 
in  the  manufacture  of  soap,  we  shall  use  the 
popular  terms  "  potash "  and  "soda,"  as  less  likely 
to  cause  confusion  in  our  readers'  minds.  Potash 
makes  soft  soap ;  soda  makes  hard  soap.  Potash 
is  derived  from  wood  ashes,  and  in  the  days  of 
our  grandmothers  soft  soap  was  the  universal 
detergent.  Potash  (often  called  Pearlash)  was 
cheap  and  abundant.  The  wood  fires  of  every 
household  furnished  a  waste  product  ready  for  its 
extraction.  Soda  ash  was,  at  that  time,  obtained 
from  the  ashes  of  sea-weed,  and  of  course  was 
not  common  inland.  Aerated  Pearlash  (Potassium 
bicarbonate),  under  the  name  of  saleratus,  was  used 
for  bread. 


66 


THE  CHE  MIS  TR  T  OF 


The  discovery  by  the  French  manufacturer, 
Leblanc,  of  a  process  of  making  soda  ash  from 
the  cheap  and  abundant  sodium  chloride,  or  com- 
mon salt,  has  quite  reversed  the  conditions  of  the 
use  of  the  two  alkalies.  Potash  is  now  some 
eight  cents  a  pound,  soda  ash  is  only  three. 

In  1824,  Mr.  James  Muspratt,  of  Liverpool,  first 
carried  out  the  Leblanc  process  on  a  large  scale, 
and  he  is  said  to  have  been  compelled  to  give 
away  soda  by  the  ton  to  the  soap-boilers,  before 
he  could  convince  them  that  it  was  better  than 
the  ashes  of  kelp,  which  they  were  using  on  a 
small  scale.  But  the  soap  trade,  as  we  now  know 
it,  came  into  existence  after  the  soap-makers  real- 
ized the  value  of  the  new  process.  Soda  ash  is 
now  the  cheapest  form  of  alkali,  and  housekeepers 
will  do  well  to  remember  this  fact  when  they  are 
tempted  to  buy  some  new  "  ine,"  or  "crystal." 

In  regard  to  the  best  form  in  which  to  use  the 
alkali  for  washing  purposes,  experience  is  the  best 
guide, — that  is,  experience  reinforced  by  judgment; 
for  the  number  of  soaps,  and  soap  substitutes,  in 
the  market  is  so  great,  and   the    names   so  little 


COOKING  AND  CLEANING.  67 


indicative  of  their  value,  that  only  some  general 
information  can  be  given. 

In  the  purchase  of  soap,  it  is  safest  to  choose 
the  make  of  some  well-known  and  long-established 
firm,  of  which  there  are  several  who  have  a  repu- 
tation to  lose  if  their  product  is  not  good ;  and, 
for  an  additional  agent,  stronger  than  soap,  it  is 
better  to  buy  sal  soda  (sodium  carbonate)  and 
use  it  knowingly,  than  to  trust  to  the  highly  lauded 
packages  of  the  grocery.  A  pound  of  sal  soda 
contains  from  four  to  five  times  as  much  alkali  as 
a  pound  of  hard  soap,  and  therefore  it  should 
be  used  with  care. 

Washing  soda  should  never  be  used  in  the  solid 
form,  but  should  be  dissolved  in  a  separate  vessel, 
and  the  solution  used  with  judgment.  The  inju- 
dicious use  of  the  solid  is  probably  the  cause  of 
the  disfavor  with  which  it  is  so  often  regarded. 
One  of  the  most  highly  recommended  of  the  scores 
of  "  washing  compounds"  in  the  market,  doubtless 
owes  its  popularity  to  the  following  directions : 
"Put  the  contents  of  the  box  into  one  quart  of 
boiling  water,  stir  well,  then   add  three  quarts  of 


G8 


THE  CHEMISTRY  OF 


cold  water  :  this  will  make  one  gallon.  For  washing 
clothes,  allow  two  cupfuls  of  liquid  to  a  large  tub 
of  water." 

As  the  package  contains  about  a  pound  of 
washing  soda,  this  rule,  which  good  housekeepers 
have  found  so  safe,  means  about  two  ounces  to  a 
large  tubful  of  water,  and  this  in  solution. 

Ten  pounds  of  washing  soda  can  be  purchased 
of  the  grocer  for  the  price  of  this  one-pound 
package,  with  its  high-sounding  name.  Nearly  all 
the  compounds  in  the  market  depend  upon  washing 
soda  for  their  efficiency.  Usually  they  contain 
nothing  else.  Sometimes  soap  is  present  and, 
rarely,  borax.  In  one  or  two,  ammonia  has  been 
found. 

For  hard  water,  a  little  sal  soda  is  almost  indis- 
pensable. Borax  is  a  very  good  cleansing  agent 
for  many  purposes.  The  sodium  is  in  a  milder 
form  than  in  washing  soda.  For  delicate  fabrics 
and  for  many  colored  articles,  it  is  the  safest 
substance  to  use. 

On  first  thought,  we  may  wonder  why  we  need 
to  add  these  chemical   agents  to  soap,  when  our 


COOKING  AND  CLEANING.  69 

grandmothers  did  without  them ;  but  we  must 
remember  that  our  grandmothers  used  soft  soap 
and  wood  ashes  for  all  the  cleansing  operations 
for  which  we  now  depend  upon  hard  soap.  It  is 
a  recognized  fact  that  soft  soap  is  much  more 
caustic  and  hence  more  effective  in  removing 
grease  than  hard  soap.  The  reason  for  this  lies 
partly  in  the  fact  that  the  gelatinous  character  of 
the  soap  allows  a  considerable  proportion  of  free 
lye  to  be  mechanically  held  in  the  mass,  and  partly 
because  potash  is  a  more  powerful  chemical  agent 
than  soda. 

Many  prudent  housewives  still  make  soft  soap 
for  their  own  use.  Many  more  add  to  the  effi- 
ciency of  the  common  soap  by  dissolving  several 
pounds  of  it  in  hot  water,  adding  about  one-third 
as  many  pounds  of  sal  soda,  and  allowing  the 
mass  to  cool  into  a  white,  soft  curd. 

A  washing  fluid,  said  to  be  of  great  value,  is 
prepared  by  the  addition  of  freshly  slaked  lime  to 
a  solution  of  sal  soda.  When  the  liquid  has 
become  clear,  alcohol  is  added  to  it,  and  it  is 
bottled  for  use. 


70  THE  CHEMISTRY  OF 

II  I  II 

Slaked  lime,   CaH202,  or  caustic  lime,  and  car- 
i  ii 

bonate  of  soda,  Na2(COs),  put  together  in  solution, 

ii  ii 

must  inevitably  result  in  carbonate  of  lime,  Ca(C03), 
I    I  ii 

and  caustic  soda,  2NaHO,  —  a  compound  much 
more  dangerous  to  use  in  excess  than  sal  soda. 
The  alcohol  dilutes  this  caustic  solution,  and  the 
little  gill  cup  used  to  measure  the  fluid  for  use, 
insures  safety.  The  mistress  who  considers  herself 
cautious  will  sanction  the  use  of  this  "fluid,"  when 
she  will  not  allow  sal  soda  to  be  used. 

Turpentine  has  been  sometimes  recommended  as 
an  addition  to  washing  fluids,  but  its  use  may  be 
attended  with  danger,  as,  when  applied  in  hot 
water,  to  the  bare  arms  of  the  laundress,  it  is 
readily  absorbed,  and  is  liable  to  cause  illness. 

There  is  a  compound  of  sodium  of  great  value 
for  laundry  and  common  use,  which  seems  to  take 
the  place  of  the  old-time  soft  soap.  This  is  sodium 
silicate,  water-glass,  or  soluble  glass.  It  is  manu- 
factured for  print  works,  and  its  common  name  is 
"water-glass,"  that  is,  glass  soluble  in  water,  and 
free  from  the  lime  or  lead  of  the  common  window- 


COOKING  AND  CLEANING. 


71 


glass.  Being  made  from  clean  materials,  sand  and 
soda,  or  potash,  it  has  no  reminder  of  the  dead 
meat  or  bone-boiler's  establishment,  as  soap  some- 
times has.  The  affinity  of  the  alkali  for  the  silica 
is  not  strong,  and  yet  it  holds  until  some  stronger 
acid  comes  in  contact  with  it.  By  virtue  of  this 
property,  it  is  said  by  the  few  housekeepers  who 
have  hitherto  had  access  to  it,  not  to  injure  the 
fabric,  even  if  used  in  excess,  and  to  give  to 
linen  the  clean,  fresh  appearance  of  new  cloth. 
It  is  hoped  that  an  agent  so  valuable  to  the 
housekeeper  may  soon  be  accessible  to  all. 

The  removal  of  spots  from  clothing  is  a  subject 
which  has  perplexed  every  woman. 

The  fabrics  upon  which  we  wish  to  operate  are 
nearly  all  colored,  and  the  modern  dye  is  such  a 
complex  and  unstable  compound  that  disaster  is 
not  uncommon. 

Chloroform,  ether,  alconol,  benzine,  turpentine, 
all  dissolve  gre-ase,  but  all  are  liable  to  show  an 
enlarged  ring  if  not  very  carefully  applied,  and  the 
water  in  ether  and  alcohol  affects  many  colors. 
Turpentine  is  useful  for  some  coarser  fabrics,  but 


72 


THE  CHEMISTRY  OF 


for  the  most  delicate  silks  and  woollens  benzine 
or  naphtha  is  the  safest,  not  injuring  the  color,  and, 
if  pure,  completely  volatile. 

For  grease  on  carpets  or  other  articles,  where 
washing  is  out  of  the  question,  absorbents  may 
be  used :  such  as  powdered  soapstone,  magnesia, 
buckwheat  flour,  etc. 

These  absorbents  are  also  sometimes  used  to 
remove  spots  other  than  those  caused  by  grease. 

Grass  stains  often  baffle  the  best  laundress.  A 
sure,  if  expensive,  solvent  for  chlorophyl  (the  green 
coloring  matter  of  plants)  is  alcohol,  if  applied 
while  the  stain  is  still  fresh.  Fruit  stains  are  generally 
removed  by  the  well-known  process  of  pouring 
on  boiling  water.  In  some  cases  oxalic  acid  is 
better. 

Red  iron  rust  is  most  readily  soluble  in  muriatic 
acid,  and  if  one  has  a  little  knowledge  of  chemical 
principles,  this  acid  may  be  of  great  use  in  the 
laundry.  It  is  very  readily  washed  out  with  clear 
water,  and  it  does  not  affect  most  fast  colors.  As 
the  iron  compound  formed  is  also  soluble,  it  can 
be  taken  away  entirely.      The  efficacy  of  salt  with 


COOKING  AND  CLEANING.  73 


lemon  is  probably  due  to  the  setting  free  of  a  small 
amount  of  muriatic  acid. 

Black  iron  stains,  as  those  from  the  inks  made 
with  iron,  may  be  best  removed  by  oxalic  acid, 
although  it  has  little  effect  on  red  iron  stains. 
The  iron  forms  a  colorless  compound  with  the  acid 
but  great  care  must  be  taken  to  remove  all  of  it  by 
a  thorough  washing.  The  difficult  solubility  of  oxalic 
compounds  makes  this  harder.  It  is  well  to 
wash  the  article  with  ammonia  water  finally,  in 
order  to  remove  the  last  traces  of  acid.  Oxalic 
acid  and  ammonia  are  two  of  the  most  useful 
agents  in  the  laundry.  For  further  details,  see 
chapter  II. 

It  may  comfort  some  young  housewife  to  know 
that  mildew  is  beyond  the  art  of  the  chemist.  It 
seems  to  be  a  vegetable  growth,  which  attacks 
the  cotton  fibre,  and  in  a  measure  destroys  it,  as 
dry  rot  does  a  stick  of  timber.  If  it  is  superficial 
only,  successive  washings  and  bleachings  in  the 
sun  will  remove  it.  If  deep  seated,  its  removal  is 
hopeless ;  as  in  other  cases,  prevention  is  the  best 
cure.    Some  cloth  is  very  liable   to   mildew,  and 


74 


THE  CHEMISTRT  OF 


servants  are  often  blamed  for  its  appearance  without 
good  cause. 

We  will  now  consider  some  of  the  preparations 
for  the  mechanical  removal  of  "  matter  in  the  wrong 
place" — tarnish  on  silver,  spots  on  paint,  etc. 

The  matron  of  fifty  years  since,  took  care  of  her 
silver  herself,  or  superintended  the  cleaning  very 
closely,  for  the  heirlooms  were  precious,  or  the 
gifts  of  friends  valuable.  The  silver  was  hardened 
by  a  certain  proportion  of  copper,  and  took  a  polish 
of  great  brilliancy  and  permanence.  The  matron 
of  to-day,  who  has  the  same  kind  of  silver,  and 
who  takes  the  same  care,  is  the  exception.  Plated 
ware  is  found  in  nearly  every  household  in  our 
villages.  The  silver  deposited  from  the  battery 
is  only  a  thin  coating,  and  is  of  pure,  soft  metal  — 
very  bright  when  new,  but  easily  scratched,  easily 
tarnished,  and  never  again  capable  of  taking  a  beautiful 
polish.  The  utensils,  being  of  comparatively  little 
value,  are  left  to  the  table-girl  to  clean,  and  of  course 
she  uses  the  material  which  will  save  her  labor. 

In  order  to  ascertain  if  there  was  any  foundation 
for  the  prevalent  opinion  that  there  was  mercury 


COOKING  AND  CLEANING.  75 


or  some  equally  dangerous  chemical  in  the  silver 
powders  commonly  sold,  we  have  purchased  sam- 
ples in  Boston  and  vicinity,  and  in  New  York  and 
vicinity. 

Thirty-eight  different  kinds  have  been  found. 
Of  these, 

25  were  dry  powder. 
10     "    partly  liquid. 
3     "  soaps. 

Of  the  twenty-five  powders,  fifteen  were  chalk 
or  precipitated  calcium  carbonate,  with  a  little 
coloring  matter,  usually  rouge. 

6  were  diatomaceous  earth. 
2    "    fine  sand  entirely. 
2    "      u       "  partly. 

Mercury  was  found  in  none.  No  other  injurious 
chemical  was  found  in  any  save  the  "electro-plating 
battery  in  a  bottle,"  which  contained  potassium 
cyanide,  KCy,  a  deadly  poison ;  but  it  was  labelled 
poison,  although  the  label  also  stated  that  all  salts 
of  silver  are  poison  when  taken  internally.  This 
preparation  does  contain  silver,  and  does  deposit  a 
thin  coating,  but  it  is  not  a  safe  article. 


76 


THE  CHEMISTRY  OF 


Of  the  nine  polishes,  partly  liquid,  five  contained 
alcohol  and  ammonia  for  the  liquid  portion ;  four, 
alcohol  and  sassafras  extract.  The  solid  portion, 
in  all  cases,  was  chalk,  with,  in  one  case,  the 
addition  of  a  little  jeweller's  rouge. 

The  caution  to  be  observed  in  the  use  of  these 
preparations  is  in  regard  to  the  fineness  of  the 
material.     A   few   coarse   grains   will   scratch  the 

II  IV II 

coating  of  soft  silver.    Precipitated  chalk,  CaC03, 

IV  II 

or  well-washed  diatomaceous  earth,  Si02,  seem  to 
be  of  the  most  uniform  fineness. 

We  may  learn  a  lesson  in  this,  as  well  as  in 
many  other  things,  from  the.  old-fashioned  house- 
wife. She  bought  a  pound  of  whiting  for  twelve 
cents,  floated  off  the  fine  portion,  or  sifted  it 
through  fine  cloth,  and  obtained  twelve  ounces  of 
the  same  material,  for  three  ounces  of  which  the 
modern  matron  pays  twenty-five  or  fifty  cents, 
according  to  the  name  on  the  box. 

Silver  is  liable  to  tarnish  from  many  causes,  some 
of  which  can  be  avoided.  Flannel  is  apt  to  con- 
tain sulphur,  and  should  not  be  used  to  wrap  up 


COOKING  AND  CLEANING.  77 


silver  articles.  Clean,  soft  tissue  paper  first,  then 
a  bag  of  Canton  flannel,  form  a  good  covering. 
Want  of  sufficient  ventilation  in  a  house  shows 
itself  very  quickly  by  the  tarnish  on  the  silver, 
caused  by  foul  air  and  coal  gas. 

Iron  and  steel  oxidize  in  damp  air,  according 
to  the  rule  that  the  presence  of  water  favors 
chemical  change.  A  little  oily  coating  will  exclude 
the  air  and  hence  no  oxidation  can  ensue. 

The  mechanical  removal  of  spots  on  paint  and 
kitchen    utensils   is   effected    by  scouring  agents, 

II  IV  II  n  IV  II 

such  as  chalk,  CaC03,  whiting  impure,  CaCOs, 
pumice    and    Bristol    brick   (silicates),  fine  sand 

IV  II 

Si02,  and  preparations  which  owe  their  cleansing 
properties  to  one  of  these  solids. 

A  frequent  source  of  annoyance  is  the  bluing, 
which  seems  to  be  indispensable  to  the  city  laun- 
dress, who  has  not  fresh  grass,  or  the  white  snow 
of  the  country  on  which  to  whiten  her  clothes. 

Three  substances  are  at  present  used  for  this 
purpose.  Indigo,  from  the  plant  Indigo  tinctoria, 
has  been  known  from  time  immemorial.  Soluble 


'78 


THE  CHE  MIS  TR  T  OF 


Prussian  blue,  a  chemical  compound  containing 
iron,  is  a  recent  invention.  Ultramarine,  the  third, 
is  a  silicate,  insoluble  in  water,  giving  a  tint  by 
means  of  the  very  fine  blue  powder,  which  is  im- 
pacted in  the  cloth. 

The  indigo  bags  of  olden  time  have  been  almost 
entirely  replaced  by  numerous  "  Soluble  Blues," 
all  of  which  are  Prussian  blue  of  greater  or  less 
strength. 

It  must  be  borne  in  mind  that  this  substance  is 
decomposed  by  the  fixed  alkalies,  and  if  the  clothes 
are  not  rinsed  free  from  soap-suds  or  washing 
soda,  mysterious  iron-rust  spots  may  appear  on 
the  linen,  caused  by  the  decomposition  of  the 
bluing.  The  general  yellowish  tint,  which  is  so 
often  seen  on  linen,  is  probably  due  to  this  cause. 

Of  fifteen  different  kinds  of  bluing  which  were 
examined,  not  one  was  anything  but  Prussian  blue. 
Here,  as  in  so  many  other  cases,  the  young  house- 
keeper who  has  had  some  training  in  a  chemical 
laboratory,  has  an  advantage  over  one  who  has  not, 
in  her  idea  of  absolute  cleanliness,  and  her  con- 
ception of  the  inexorable  laws  of  chemical  change. 


COOKING  AND  CLEANING. 


79 


A  long  chapter  might  be  written  on  the  subject 
of  economy  in  the  case  of  the  multitude  of  chemical 
preparations  so  freely  offered  for  sale.  There  is 
so  much  for  the  young  housewife  to  do  that  she 
is  tempted  by  every  promise  of  making  labor  easier, 
and  is  very  ready  to  try  anything  that  is 
recommended. 

She  thinks  that  if  her  servants  are  provided  with 
all  the  modern  appliances  for  doing  work  quickly 
and  well,  it  is  their  fault  if  they  do  not  ac- 
complish it.  She  forgets  that  the  past  generation 
of  women,  who  succeeded  in  keeping  their  families 
healthy  and  happy,  brought  brains  to  the  work ; 
they  knew,  too,  the  properties  of  the  substances 
they  used,  because  they  prepared  them  at  home. 

When  American  girls  will  learn  to  apply  Chem- 
istry and  Physics  to  every-day  life,  we  may  hope 
for  a  speedy  solution  of  the  servant-girl  ques- 
tion. 


CHAPTER  II. 


CHEMICALS  FOR  HOUSEHOLD  USE. 


I. 


Acids. 


HERE  are  three  acids  which  should  be  found 


in    every    laundry    cupboard :     acetic  acid, 

IV    I    II  II 

C2H402;  muriatic  or  hydrochloric  acid,  H CI;  and 


oxalic  acid,  C2H.04. 

Vinegar  can  be  used  in  many  cases  instead  of 
acetic  acid ;  but  vinegar  contains  coloring  matters 
which  stain  delicate  fabrics,  and  it  is  better  to 
use  the  purified  acid,  especially  as  the  so-called 
vinegar  may  contain  sulphuric  acid. 

If  soda  has  been  spilled  on  black  silk  an  ap- 
plication of  acetic  acid  will  usually  restore  the 
color. 


IV 


ii 


THE  CHEMISTRY  OF  COOKING,  ETC,  81 


Many  of  the  bright  blue  flannels  and  other 
fabrics  found  at  the  present  time  in  our  markets 
owe  their  brilliant  shades  to  an  acid  compound  of 
a  coal-tar  color,  and  as  soon  as  they  are  washed 
in  soap  or  ammonia,  the  alkali  neutralizes  the 
acid,  and  the  color  becomes  pale  and  faded  in 
appearance.  If  acetic  acid  or  vinegar  is  added  to 
the  second  rinsing  water,  the  bright  color  is  in  all 
such  cases  restored.  This  fact  was  discovered  by 
accident,  and  is  well  worth  remembering.  Of 
course,  not  all  shades  of  blue  are  made  with  this 
compound,  and  hence  not  all  faded  blues  can  be 
thus  restored.  It  is  well  to  test  a  bit  of  the 
cloth  before  washing  the  whole  garment. 

A  weak  acid  like  acetic  acid  is  safe  to  use  on 
many  fabrics  which  would  be  injured  by  a  strong 
acid. 

Muriatic  or  hydrochloric  acid  is  useful  in  a 
multitude  of  ways.  By  means  of  it,  the  writer 
once  restored,  in  a  few  minutes,  a  delicate  blue 
cambric  dress,  which  had  been  quite  ruined  by  nu- 
merous large  stains  of  red  iron  rust.  The  cloth  was 
laid  over  a  large  bowl  half  filled  with  hot  water, 


82 


THE  CHEMISTRY  OF 


and  the  spots  thus  steamed  were  touched  with  a 
drop  of  the  acid,  and  as  soon  as  the  iron  was 
dissolved,  the  cloth  was  plunged  into  the  water  to 
prevent  injury  to  the  cotton  fibres.  All  the  spots 
were  thus  dissolved  off ;  the  garment  was  then 
quickly  rinsed  in  several  waters,  and  finally  in  water 
containing  a  little  ammonia,  which  neutralized  any 
trace  of  acid  still  remaining.  This  process  is  by 
far  the  best  for  removing  red  iron  stains  from 
white  cloth. 

Porcelain  or  china,  stained  with  iron,  can  be 
cleaned  with  muriatic  acid.  For  the  porcelain  or 
enamelled  water-closet  basin  it  is  especially  useful, 
but  the  acid  must  be  removed  by  rinsing  with 
water  followed  by  a  little  alkali  to  save  the  iron 
pipes  below. 

The  acid  must  not  be  used  on  marble,  as  it 
dissolves  it  with  great  rapidity,  and  the  polish  is  lost. 

The  property  which  muriatic  acid,  in  common 
with  the  so-called  stronger  acids,  possesses — that  of 
liberating  carbonic  acid  gas  with  brisk  effervescence 
from  its  compounds,  renders  this  acid  valuable  for 
the  detection  of  carbonates. 


COOKING  AND  CLEANING.  83 


For  instance,  if  the  label  of  a  washing  powder 
claims  it  to  be  something  new,  and  requires  that 
it  be  used  without  soda,  as  soda  injures  the  clothes, 
it  can  be  tested  as  follows :  Put  half  a  teaspoonful 
of  the  powder  into  a  tumbler,  add  a  little  water, 
then  a  few  drops  of  muriatic  acid.  A  brisk  effer- 
vescence will  prove  it  to  be  a  carbonate,  and  if 
the  edge  of  the  tumbler  is  held  near  the  colorless 
flame  of  an  alcohol  lamp,  the  characteristic  yellow 
color  of  sodium  will  complete  the  proof.  If  the 
acid  is  added  drop  by  drop  until  no  more  effer- 
vescence occurs,  and  there  remains  a  greasy  scum 
on  the  surface  of  the  liquid  in  the  tumbler,  the 
compound  contains  soap  as  well  as  sal  soda,  for 
the  acid  unites  with  the  alkali  of  the  soap  and 
sets  free  the  grease. 

If  some  very  costly  silver  polishing  powder  is 
offered  as  superior  to  all  other  powders,  a  drop 
or  two  of  muriatic  acid  will  decide  whether  or  not 

II  IV  II 

it  is  chalk  or  whiting  (CaC03)  by  the  efferves- 
cence or  liberation  of  the  carbonic  acid  gas. 

Oxalic  acid  is  purchased  in  white  crystals, 
and  for  use  a  saturated  solution  is  made ;  as  one 


S4 


THE  C  HEM  IS  TR  T  OF 


part  of  it  dissolves  only  in  several  parts  of  water,  it 
is  well  to  keep  an  excess  of  the  crystals  in  the  bottle. 
It  is  somewhat  poisonous,  and  should  not  be  left 
in  the  solid  form  within  reach  of  careless  people. 
A  small  bottle  of  liguid  can,  however,  be  kept 
with  other  laundry  articles. 

This  acid  is  the  only  efficient  means  which  is 
known  to  the  writer,  for  removing  the  shoe- 
leather  stains  from  white  stockings.  It  will  take 
out  most  fruit  stains  on  napkins  and  from  the 
fingers ;  for  the  latter  purpose  tartaric  acid  will 
also  serve. 

Oxalic  acid  is  invaluable  to  the  housekeeper 
as  a  means  of  removing  black  iron  stains,  such  as 
those  caused  by  the  iron  inks. 

It  is  a  more  powerful  acid  than  acetic  acid, 
and  must  be  carefully  removed  from  cloth  by 
rinsing  with  water  and  finally  by  ammonia. 

Oxalic  acid  is  very  efficient  as  an  agent  for 
cleaning  brass,  and  seems  even  safer  to  use  than 
acetic,  as  the  compound  of  the  latter  with  copper 
salts  is  one  of  the  most  dangerous  of  the  copper 
compounds. 


COOKING  AND  CLEANING. 


85 


TV  II 

Sulphurous  acid  gas  (S02)  is  obtained  by  burn- 
ing sulphur,  and  is  the  well-known  agent  for 
bleaching.  It  will  often  remove  spots  which  noth- 
ing else  will  touch.  The  cloth  or  other  substance 
should  be  moistened  and  held  over  a  bit  of  burning 
julphur ;  as  the  agent  is  an  acid,  the  same  pre- 
cautions must  be  observed  as  in  the  case  of  the 
other  acids,  as  to  the  removal  of  the  corrosive 
substance. 

2.  Alkalies. 

The  uses  of  ammonia  water  and  ammonium  carbon- 
ate, have  been  considered  in  the  text ;  a  precaution 
to  be  taken  is,  that  the  bottles  should  not  be  kept 
with  other  bottles  containing  liquids  for  internal  use, 
as  distressing  accidents  have  occurred  from  swallow- 
ing ammonia. 

Caustic  soda  or  potash  is  better  for  greasy  tins 
than  soap ;  a  swab  should  be  used  to  apply  it, 
however,  as  it  is  corrosive  to  the  hands.  Silicate 
of  soda  may  also  be  used  for  this  purpose. 

Some  alkali  should  be  always  at  hand.  The 
alkali   compounds,   sodium   carbonate    (sal  soda) 


86 


THE  CHEMISTRY  OF 


I    V  II  I  II  II  IV II 

Na2C03  +  H  IO  H20  and  calcium  carbonate  CaC03, 

are  of  daily  use  as  has  been  already  explained  in 
the  previous  chapter. 


BOOKS  FOR  REFERENCE. 


For  Teachers: 

"  History  of  Chemical  Theory." 

A.  Wurtz. 

Translated  and  edited  by  Henry  Watts. 
"  Elementary  Manual  of  Chemistry." 

Eliot  and  Storer. 

"Physiology  and  Hygiene."     (Chapter  on  Digestion.) 

Huxley  and  7"oumans. 

"Treatise  on  Chemistry." 

Roscoe  and  Schorlemmer. 

For  General  Readers  : 
"  Elements  of  Chemistry." 


Le  Roy  C.  Cooley. 


COOKING  AND  CLEANING.  87 


"The  Birth  of  Chemistry." 

Rod-well. 

"Chemistry  of  Common  Life." 

Johnston  and  Church  {?ieiv  edition). 

"The  New  Chemistry." 

J.  P.  Cooke. 

"Lessons  on    Elementary  Chemistry." 

Henry  E.  Roscoe. 

"  Fermentation." 

Schntzenberger. 

"  Vortrage  uber  die  Entwickelungsgeschichte  der  Chemie 
in  den  letzten  Hundert  Jahren." 

Dr.  A.    Ladenburg . 


Table  of  some  common  elements  with  their  atomic 
weights  and  symbols. 


NAME. 

SYMBOL. 

ATOMIC  WEIGHT. 

Hydrogen 

H 
I 

CI 

I. 

Chlorine 

35*5 

Sodium 

I 

.Na 

23- 

Potassium 

I 

K 
I 

Ag 

II 

O 

II 
Cu 

39.1 

Silver 

Oxygen 

Copper 

108. 
16. 
63-4 

THE  CHE  MIS  TR  T  OF  COOKING,  ETC. 


NAME. 

Calcium 

Barium 

Lead 

Zinc 

Boron 

Gold 

Iron 

Aluminum 

Tin 

Silicon 

Carbon 

Nitrogen 

Arsenic 


SYMBOL. 

ATOMIC  WE 

II 

Ca 

40. 

II 

Ba 

i37- 

II 

Pb 

207. 

II 

Zn 

65.2 

III 

B 

1  r. 

III 

Au 

197. 

II  IV 

Fe  or  Fe 

56. 

II  IV 

Al  or  Al 

27.4 

II  IV 

Sn  or  Sn 

11S. 

IV 

Si 

28. 

IV 

C 

12. 

III  V 

N  or  N 

14. 

III  V 

As  or  As 

75- 

INDEX. 


Page. 

Absorption  of  Food,    ...  44 

Acetic  Acid,   80 

Acids : 

Acetic,  •  .  .  •  •  .•  .•  80 
Hydro-chloric  or  Muriatic,  80 

Oxalic,  73-80 

^  Tartaric,   49 

Acid  Phosphate,   49 

Albumen,   38 

Albuminous  Food,    ....  41 

Alcohol,  29-59-71 

Alkalies,   85 

Caustic,   62 

Volatile,    62 

Alum,  33-49 

Ammonia,  61-63-64-85 

Ammonium  Carbonate,     .  63-64-85 

Assimilation,   44 

Atomic  Weight,   5 

Baking  Powders,  32*49 

Benzine,  59-7* 

Bluing,   77 

Books  for  Reference,    ...  86 

Borax   68 

Bread,   24 

Fermented,   28 

Reason  for  Kneading,     .  28 
Temperature  for  Ferment- 
ing   28 

Temperature  for  Baking,  29 

Snow- Bread,   30 

Soda-Bread,  ....  31-32-33 
Carbonic  Acid,  Gas,  .    .    .  27-31-49 

Cassium;   61 

Chemical  Change,    ....  1-16 

Element,   3 

Equation,   11 

Reaction,  ......  11 

Chloroform,   ji 


Pagk. 

Cleaning : 

Brass,   84 

Brushes,   64 

Glass,   64 

Paint,   .   64 

Silver,   74*75 

Cooking;,   45 

Of  Starch,   23 

Of  Nitrogenous  Food,     .  39 
Cost  of  Nitrogenous  and  Vege- 
table Diet  in  Germany 

compared,  .    .    :    .    .  48 

Cream  of  Tartar,   32-49 

Danger : 

Acetic  Acid  on  Copper,  .  84 

Ammonia,   85 

"  Battery  in  a  Bottle,"    .  75 

Hardwater,   40 

Soda,   39 

Turpentine  in  Washing,  .  70 

Diastase,   20 

Ether,   59-71 

Fats   34-35 

Decomposition  of   .    .    .  47 

Fruit  Stains,   72 

Glucose,   21 

Gluten,   27 

Grass  Stains,   72 

Grease  on  Carpets,  ....  72 
Growth  Nitrogenous  Food  re- 
quired for,   37 

Heat— Artificial,  .....  16 

Source  of  in  Animals,      .  17 

Heat-producing  Food,  ...  18 

Ink  Stains,   73 

Iron,  Black  Stains  of    .    .  73-82-84 
Rust,    ......  72-78-81 

Law  of  Definite  Proportion  by 

Weight,   i» 


90 


INDEX. 


Page. 

Lime,   -0 

Lithium,   61 

Magical  Washing  Fluids,  .    .  64 

Mildew,   7, 

Milk   \\ 

MuiUticAcid   8i 

Nitrogen,   37 

Percentage  of  in  Food,  .  50-53 
Required  in  Growth  and 

Work,   ,7 

Oils,  34.35 

Oxalic  Acid,   83 

Pearl  Ash,   65 

Plate  Powders,   75 

Potash,  65-85 

Potassium,   61 

Potassium  Cyanide,  ....  75 
Princ  pies  of  I  >iet,  ....  40 
Properties  of  Substances,  .  .  1 
Proportion  of  Nitrogenous 

Food  required,  ...  46 
Ptyalin  in  Saliva,  ....  22 
Relation  of  Climate  to  Food,  40 
Removal  of  Spots,  .  .  .  71-72-85 
Residues  from  Baking  Pow- 
ders,  32-33 

Restoring  Color,  80-81 

Roche  lie  Salts,   49 

Rubidium,   61 

Rust  of  Iron,  72-81 

Sal  Soda,  65-67-85 

Salt,  32-47 

Saponin,   57 

Silver-Tarnish,   74 

Snow-Bread   30 

SoaP'-  ,  55-58 

Bark,  ,  57 

Berry  Tree,   57 

Soda,  .    .......  33-49-85 

Soda  Ash,   66 

Soda  Bread,  31-32-33 

Sodium,   61 

Carbonate,   67 

Silicate,   70 

Soft  Soap,   .......  69 


Page. 

Soluble  Glass,   70 

Stains,  71-72-80-82-84 

Starch,                               .  ,8 

Chemical  Changes  of  .    .  20 

Cooking  of   23 

Sugar   20 

Tables: 

I.    Atomic  Weights,  .  5 
II.    Exchangeable  Val- 
ues,   7 

III.  Interchangeable 

Values,     ...  9 

IV.  Mineral  Acids,  .    .  14 
Baking  Powders     ...  49 
Composition  of  Some  Ani- 
mal Food,   50-54 

Composiiion  of  Some 

Vegettble  Food,     .    .  51-54 
Comparative  Digestibility 

of  Food,   52 

Daily   Weight  of  Food 

Required,   53 

Percentages  of  Waste,    .  54 

Tannin,   47 

Temperature  for  Fermenting 

Bread,   28 

For  Baking  Bread,     .    .  29 

Tests  with  Muriatic  Acid,     .  83 

Tobacco,   47 

Turpentine  59-70-71 

Transfer  of  Force- Producing 

Power,   42 

Unit  of  Value,   6-7 

Vinegar,   80 

Volatile  Alkali,   62 

Yeast,   27 

Yellow  Tint  on  Linen,  ...  78 

Washing  Fluids,   69-70 

Washing  Woollens,  ....  62-63 
Water  as  the  Heat- Regulator 

of  the  Body,   ....  46 

Water  Glass,   70 

Wood  Ashes,   57-59 

Work,  Nitrogenous  Food  Re- 
quired for   37 


'7  f> 


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